Well if you have the Dark knight returns, not much more you need, tis awesome. Try the Killing Joke, although it isn't very long.
Other than those two, I'm not a big fan, so I couldn't recommend any others.

Mhm, I'd recommend The Killing Joke too, however, it's a mite short but excellently written & drawn. Actually, it's more of a Joker novel really, as Batman himself only actually shows up in a few panels.

You have to read Arkham Asylum its a totally different look of batman cosmology and especially its villains
also no man's land is exceptionally well made and a personal favourite

Killing joke is cracking,
My favorite series of Batman by far is "No Mans Land" which occurs just after an earthquake and a plague hit the city and the government has sectioned Gotham off from the rest of the USA and the villains take up parts of the city itself and gangs run rampant. Nobody can connect to the outside.

Knightfall is another good series where Batman meeks his maker, very hardcore, some dude messes him up and a crazy cultist takes Batman's place.

Once you get into Batman, 2 really groundbreaking and funny in their own way novels by Frank Miller "The Dark Knight Returns" and " Dark Knight Strikes Again" which are about Batman when he is crazy and old the the government are turning into a load of dicks...

I really didn't like "hush" it seemed rather thin on plot and character depth.

Also check out Spawn vs Batman by Mcfarlane and Batman &Judge Dredd Judgement on Gotham.

Thry Otherworld novels and Child of Dreams, a Batman Manga.

Batman Gothic by Grant Morrison. I heard his Black glove storyline was really good too.

Batman Black and White is worth a look.

Batman War on Crime has amazing artwork.

Batman Year One (bit short)
Batman Knightfall (amazing story, weak art)
The Dark Knight Returns (awesome with toast)

EDIT: Thinking about it get the Knightfall audio book. That the most Batman thing I've ever had, 3 hours of brilliant. Perfect for a long flight. Cheap on CD now.

you should also pick up Kingdom Come, its one of the best DC series EVER.

Frater Perdurabo:
no man's land is exceptionally well made and a personal favourite

Serious_Stalin:
My favorite series of Batman by far is "No Mans Land" which occurs just after an earthquake and a plague hit the city and the government has sectioned Gotham off from the rest of the USA and the villains take up parts of the city itself and gangs run rampant. Nobody can connect to the outside.

No man's land is an awesome series if its the one i'm thinking of; batman goes away for a year or so for some reason I forgot and comes back to find gotham turned into hell on earth with gangs holding turf wars all over the place (each supervillain has his or her own gang of followers).

Also for a shot read theres one I think its called "masks"? Gives you a right good mindfucking if you'll excuse the phrase. Couldn't find the one I meant becuase I couldn't remember the story-

While lookng for it I found this (IGNs top 25 batman graphic novels) for you though so its all good:
http://uk.comics.ign.com/articles/624/624619p1.html

Hyper-space:
you should also pick up Kingdom Come, its one of the best DC series EVER.

Yes yes Kingdome come. How could i forgot such masterpiece. Its an amazing novel with imaculate art and tremendous storyline. It isnt exacly batman novel but a DC universe novel.Its a must have novel

Its not a grahic novel but still. Look up for Alex Ross. His paintings of Batman are the best.

I'm going to garner a little bit of controversy here and say 'All Star Batman and Robin',it's written by Miller and illustrated by Lee (who is a fucking genius) and it's supposed to bridge the gap between Year one/Dark victory and The Dark Knight returns, what it actually is is a hilarious, fanboy aggrivating spin on the series. The batman in All star is like the Dark Knight as imagined by a 13 year old, he's a grinning, semi psychotic with a foul sense of humour and a love for profoundly over the top dialogue. It starts with lines like this

and gets better from there. I honestly can't recomend it enough.

Oh and stay away from the Dark Knight strikes again, it's awful.

Hyper-space:
you should also pick up Kingdom Come, its one of the best DC series EVER.

Seconded, it is truly amazing. Ross' art is awesome.

Decoy Doctorpus:

Oh and stay away from the Dark Knight strikes again, it's awful.

Also seconded. I couldn't believe how piss poor it was after 'The Dark Knight Returns'

galletea:

Hyper-space:
you should also pick up Kingdom Come, its one of the best DC series EVER.

Seconded, it is truly amazing. Ross' art is awesome.

Decoy Doctorpus:

Oh and stay away from the Dark Knight strikes again, it's awful.

Also seconded. I couldn't believe how piss poor it was after 'The Dark Knight Returns'

To be honest I wasn't super keen on the Dark Knight returns to be honest. It was awesome, but I've always felt that bringing in other DC characters always weakened Batman as a series. I suppose I just liked the more realistic bent. Plus Miller's idea of the future is hilariously off base.

Update. I'm currently reading 'Joker' by Azerello (of 100 bullets fame) and it's fucking awesome. Give it a shot.

oh and also pick up JSA: Liberty files, batman as a WWII agent is awesome

edit: for a gritty batman novel you should check out Batman: year 100

It's not batman, but I read it just a few days ago and I'm now obsessed with graphic novels.

Watchmen.

Was blown away, seriously pick this one up. Good length too, I'd say... 6 hours.

I don't think that the Dark Knight strikes again series weakened Batman, Batman was always meant to be some crazy genius who was pretty close to going over the edge. This is a long time after the Batman we know today, when he is aging and his mind is deterioating the ridiculous stuff he does is almost believable when you consider his power and genius its just he would never do it in the state of mind which he is in in the other series.

you must read Batman: Year one, No Man's Land, Bruce Wayne: Murderer, Knightfall and Arkham Asylum

Are you just looking for batman? Because there are many, many great graphic novels out there that are non-batman. I would personally suggest V for Vendetta, League of Extraordinary Gentlemen, Watchmen of course, and anything else Alan Moore.
If you do just want batman, then ignore me. =p

I've got Batman Year 100, its the similar premise to DKR and DKSA, but he's even older and poorer, crazier too. Its also nice as other DC characters don't clutter the story like DKSA.

EDIT: Try and find the Batman: Gotham Knight DVD, its like the Animatrix for Batman. It features Deadshot doing a 180 from precise crazy range sniper to "Spray 'n' Pray" nutter.

has anyone here read Civil War? i know its from marvel but still

Arkham Asylum. It has a kickass plot behind it, love the way all the villains are portrayed, shows the nightmare atmosphere that is Arkham, and is in general highly insane.

It's also a comic made by Dave McKean. Therefore it is good by default.

Hyper-space:
has anyone here read Civil War? i know its from marvel but still

Yes! Most of it was great, I loved the main plot and the spiderman and Black Panther side plots were awesome. The Wolverine one would have been great but the art made me sick. Amazing twist at the end as well.

Did they not just come out with the new one called The Joker?

Just picked up "DC universe, the stories of alan moore" has 13 stories including "The killing joke" and another batman titled "mortal clay". Was $20 and is 303 pages long.

Haven't gotten around to reading it yet :P Just based off of Watchmen it should be good so thought I'd mention it.

makeitvab:
It's not batman, but I read it just a few days ago and I'm now obsessed with graphic novels.

Watchmen.

Was blown away, seriously pick this one up. Good length too, I'd say... 6 hours.

Reread chapter 5. The whole chapter is symmetrical with the split page being the only panel the covers more than one page in the entire series.

If Alan Moore's name is on the cover read it.

Black Hole and Love and Rockets are both fairly good, they are not action orriented like Batman but the stories are still really great. If you are into memoirs, Maus I & II and Fun Home are both excellent stories. JLA : Earth 2 is fairly good also.

4-5 hours is way to short of a time to read a comic. Slow down and look at the panels more carefully, trust me there is a lot that you missed.

The Ninja's list of Graphic Novel Recommendations:
Sandman Series by Neil Gaiman
V for Vendetta By Alan Moore
Watchmen By Alan Moore
Bone series by Jeff Smith (this one is bit on the 'made for children' side but still good)

Nonfiction:
Persepolis (dunno author)
Maus by Arthur Spiegelman

Manga (order of Excellence):
Excel Saga
Black Lagoon
Blade of the Immortal
Gantz

There was one with Batman and Dracula that was pretty good, wait there were two of those, and Watchmen, I also suggest anything with LOBO in it, but you better have a strong stomach for those as Lobo tends to kill damn near everyone he incounters, that being said Lobo is still funny as hell.