Best Marathon Anime?

So me and my friends have gotten into the habit of marathoning anime together and I was wondering what you guys would recommend in the way of anime that is good for this.

So far we've marathoned Yakitate Japan, Evangelion, Angel Beats, Panty and Stocking and Hetalia. Suggestion?

Tatami Galaxy is pretty nice for marathoning. I marathoned it when I watched, and the episodes really fit nicely when watched together.

Maybe Kaiji as well. The second season of it is coming out soon, so if you haven't seen it you may wanna give it a watch.

YuYu Hakusho.

Not just cause it's my favorite anime, but because it's awesome, lengthy, and extremely fluent when watching in it's entirety.

School Days. Do it.

Suzumiya Haruhi no Yuuutsu

For sheer randomness and laughs:
Lucky Star

Just for laughs:
Seitokai no Ichizon
Seitokai Yakuindomo
Azumanga Daioh
School Rumble

The two Seitokai anime are pretty short, so they're good for short bursts (and lots of laughs). School Rumble, on the other hand, is very long; I haven't even gotten around to watching the entire damn thing yet.

Seitokai no Ichizon is possibly one of the funniest I've seen.

Dragon Ball Z!
Best anime ever...

I like a good shonen for marathons. I had a great time marathoning the 54ish episodes of FMA:B that were out on my spring break last year. Code Geass, TTGL, Baccano!, Durarara and generally balls-to-the-walls anime are a lot of fun.

And you can't go wrong with the classics. GitS, Cowboy Bebop, etc.

Dragon Ball Z!
Best anime ever...

Haha I remember marathoning dragonball Z for like a week (or at least a few days, don't remember how long it took exactly) straight with only breaks for food and sleep. BEST WEEK EVER

Funny how someone mentioned School Days, just watched that a couple weeks ago. You could easily marathon Escaflowne, it works really well.

Code Geass, TTGL, Baccano!, Durarara and generally balls-to-the-walls anime are a lot of fun.

Seconding this. It's really fun to marathon balls-to-the-walls anime with friends, since you're a lot more excited and feel more involved. Definitely great to do with friends. TTGL is arguably the perfect watch for this.

Of course, TTGL can be easily marathon'd as well, highly recommending that.