With my friends a good multiplayer game is what brings us together in a session of beer, laughs and cries of "OOOOOH!!" when someone wins/loses. With my siblings, my brother, being a sports nut, loves sports games. I've never been attracted to sports simulations so I don't play with him, however the recent(ish) exception to this was Wii Sports. He does however like any kind of FPS but frankly he sucks at all of them, so it's not much fun playing with him.
My sister on the other hand will play anything with me, and whilst she's not an expert at much we do still have a few laughs.
When it comes to gaming with my GF, it's really (and this has been true in all my relationships) a case of watch me play and praise me when I do something good, for whatever reason they have in mind, still it creates fond memories.
I think really gaming with other people has to be a light activity. I know how lame it is when your playing a game involving strategy with a friend and you/he does something wrong, sending him into a mood and drastically lowering the fun of the game and raising the awkwardness. And the worst case I ever saw of this was in Mario Smash Strikers...

Sole Caliber 3 and guitar hero sessions at my place happen pity often when we drink.

I live with a few friends we often all join the same fps server and same team and work together, we also play on opposite teams competitively but always in kind of a pure pwnage joking style. TF2 and cod4 are out big ones right now.

I used to have a gf who played kingdom hearts and alot of jrpgs but teaching her anything else seemed impossible.

When it comes to friends, they all pretty much play games in some way. I usually don't play multiplayer with other people often lately unless it's Guitar Hero, but that seems due to the fact that a lot of titles are designed for huge groups of people instead of just a handful. Even so, I have a large source of folks whom I can talk with, and if I ever need to, play with.

Family, on the other hand, is a different matter. My brother enjoys watching me play games when I'm home, and co-op is common for games like Halo and Gears of War. The problem is the rest of my family. I understand having to be careful of what I play when it comes to my two year old niece, but even if I have a family friendly game it's a pain not getting nagged to Hell when I try and play when anyone else is home. I can work time in there, but it's almost like my family refuses to allow me to play games unless it's midnight or past....which just doesn't fly with me. I wouldn't be surprised if, halfway through this Thanksgiving Break, I just hooked my 360 up to my brother's shitty TV. But hey, desperate times call for desperate measures.

As for girlfriend, my ex didn't mind playing some games like Burnout and fighters, and very much enjoyed the Wii, but for the most part didn't play much. Haven't been able to find a girl since then that's mature, let alone a gamer (and not that she was all that mature, either...).

I play Mario Strikers and a few other games with my friends with their Wii, but the main challenge was my wife, who is not really the gaming type at all.

Eventually, I found what works, which is that we occasioanlly play fighting games (Soul Calibur) on the PS2, but mostly Diabloish games on it, we had alot of fun with Baldur's Gate Dark Alliance and more recently have been enjoying Champions of Norrath.

Right now, my girlfriend and I fight for control of the 360 and, by extension, Assassin's Creed. Before that, I played R6:Vegas with some regularity until my friends decided to jump ship to COD4 :(

I think the holy grail of family and friends are the party games. Things like Super Monkey Ball, which only uses the joystick and A...WarioWare, which is just as confusing to everyone...Mario Party, etc. Since normally when a group of 4 people get together, most other games are going to be easily dominated by one person, I like to fall back on those.
Co-op is also good, when it's there. I think more games should try to include it.

Most of my friends are PC gamers, and we have LAN parties. Thirty good friends in one room all on the same Counterstrike server is a lot of fun. Every October for the last five years we've had a huge LAN we dubbed Dorktoberfest. We play other things aside from Counterstrike, but most of them are shooters. At least a few guys can't seem to handle anything more complicated than that, or don't want to.

Most of my friends play both PC and X360, so it usually varies on what we play. Counterstrike, warcraft 3, diablo 2, starcraft, and total annihilation for PC lans. Rainbow six: vegas, Halo CE, 2, 3, Call of duty 4, and Splinter Cell: Chaos theory is for 360 lans. It's also been a great release year, so we often end up just at each other's houses playing different games at the same time. My last girlfriend beat me at guitar hero and Super smash Bros, but she was asian so it was an unfair match up :P. My sister and I used to play Pokemon puzzle league (greatest game ever).

With friends, I mostly play Super Smash Bros or Mario Kart. Four-player drunken Mario Kart at three in the night has a mysterious charm that's quite unlike everything else I ever experienced.

My girl loves the Mii channel on my Wii so we spend quite some time on games in which the Mii's participate, Wii sports tennis being the favorite. And we've spend many an evening trying to beat each other at Mario and Yoshi since it came to the virtual console.

I usually just host a party on xbox live with my friends. if i have people over its usually DOA, mortal kombat or metal slug. and i try to keep my girlfriends away from my games.

i've always found that either a multiplay FPS like Halo works really well, or usually something on a nintendo counsel, either the GCube or the Wii. right now me and my friends have been playing Naruto 4 on import for the gamecube as if it were pure virtual crack-cocaine, but it is fun. even if your not really an anime fan or a fan of naruto, its still a fun game. i was introduced to the series by the game.

But going back to nintendo counsels, there has always been something about nintendo that is just good old fashioned fun. since super nintendo, all of their systems have had 4 controller ports built into the counsel, greatly supporting the ease for party gaming. and their games tend to reflect this, like with the mario party series, or Wii sports, or GoldenEye on the N64, Mario Cart games, and so forth. while tending to be more cartoonie, nintendo has always offered a multitude of mostly fun 4 or more people games intended for large groups, and it makes gaming more fun to get everyone involved.

Hmm... When my boyfriend and friends (all bf's guy-friends) and me are all together, we generally play a lot of Super Smash Bros Melee (and soon Brawl, hopefully!). As for gaming-differences, my bf seems awfully against PS2 multiplayer gaming, so I never get to bring out my multitap and games I've invested quite a bit in. ^^;

At LANs we play a lot of FPS games because only a few people are willing to play Starcraft or Gunbound, so it's basically whoever's pickiest about games gets to choose the set of games we play (again, all FPS, bah). @_@a Kind of makes me mad now that I think about it. Haha.
Really, I'd like to play more StarCraft, Toblo, Gunbound, or especially something co-op, but all we end up playing is FEAR Combat, HL2 Deathmatch, and, maybe, SourceForts. ^^;

My ex was a complete crpg freak, she had every Nintendo console and loved the likes of Tales of Symphonia (she even did a 100% run in that one, which is SICK) and Baten Kaitos.

However, she had this thing where she refused to play games together with me. She had to play by herself. Even other games. Bit odd, from my perspective.

Yeah my friends and I have different tastes too. Good thing Nintendo created Smash Bros. Melee. We cant wait for Brawl(I called Sonic!). AS for my girlfriend, she like Guitar Hero and Halo 3. Yes I said Halo.

My friends are very fussy about the games they play, I can't get some of them to give up World of Warcraft. I've played it myself for two years with most of them but now I can't possibly go back and they can't possibly quit. My really close friends will generally buy any console game I do or other games such as Team Fortress 2 and play with me so I guess I'm pretty lucky.
My ex boyfriend was a twat and couldn't take defeat very well though. I guess it's the taste in games and other 'forms of entertainment' that brought us apart.

For me that really depends on which friend I have around. There're at least five friends I have who're perfectly okay with playing a two player game of any sort or even trading off playing a survival horror game, 1P shooting game or even just watching others play, though I've one friend that just HAS to play recent, 2P, co-op games, either they be fighting, third or first person shooters. I know it sounds awkward to mention, but I find it funny that my very first-ex girlfriend LOVED playing racing games (especially in bumper-cam or behind the wheel perspectives) and any game that featured T&A.

Most of the games we end up playing are some form of shooter, either co-op or deathmatch, or some sort of racing game (example; Halo, Gears of War, Forza 2, GT3...). I enjoy all the games they pick, even Halo when I'm paired with/against someone (insta-kill with rocket launchers is always fun) even if I'm not that good at the game.
Though when we start drinking it's usually Guitar Hero or RockBand.
A few of my friends like to bust out some fighters, which are fun for a while but don't last to long. There are the occasional RPGs, which we'll generally take turns on.

Family doesn't play, and la boyfriend or an ex does not exist. Hoo and rah!

Friends: we play World of Warcraft. However, since we're all scattered all over the place level-wise, and some of us like PvP and some hate it, it's more of a chat window open while doing our own thing. We do take turns running each other through instances though.

If I'm at a friend's house with a Wii, we'll play Wii games. So far, we've played Wiiplay, Wiisports, and Rayman Raving Rabbids. We also like Guitar Hero.

Family: thinks I'm a freak. Which is bizarre because my sister used to dominate Super Mario 1, 2, and 3, as well as Legend of Zelda. But that was a long time ago.

No boyfriend currently. Can't decide if this is a good thing or a bad thing. Ex did play a lot of history type games (MoH, Panzer General) that I just was not interested in.

Family: mario party/ mario kart/ mario anything.

Friends: Smash brothers/ World of warcraft/ Halo.

Girlfriend: Puzzle Quest/ World of Warcraft.

those are my choices.

With my friends, it's usually Halo 3 over Live or clustered around my smallish HDTV. None of my friends have CoD4 yet, although we all plan on getting it soon; play will likely transfer to that once we all have it.

Play with my family is, sadly, nonexistent. My mom and dad can barely remember the names of the games I play. My sister sometimes plays the Wii, but that's a rare occurrence.

Family? Heh, my mom can't even play Lego Star Wars.

Friends: Halo 3, WoW, occasionally TF2.

When I play games with my siblings I play Halo with my little brother and DDR with my sister. My parents don't play games with me no matter how hard I try. My friends and I are usually playing Call of Duty 4, and I was just able to get my girlfriend to play Rock Band with me. She had fun with Portal early on but gave up near the end even though I offered to help her with the game.

Almost all of my friends plays ecxat same games like me, so sometimes we all gather up in one place to make monstrous LAN party. 20 best friends at one place, playing RA2(best game ever), CS, HL, NFS, Quake 3 etc. what else can be better than that?
As for my family, my brother used to play Sport games, but now he's into Photoshop, so he doesn't play any games at all. My father is a huge NFS fan, so after every new release he becomes no-lifer for about 2 weeks. It's rly sad that my mother doesn't play any games at all...