Personally I'd like to see the arcade version of Xenophobe, atari version of Haunted House, arcade version of Splatterhouse, Black Tiger & Bosconian, early PC/C64 game of Friday the13th, as well as the arcade of the original vector game of Star Wars. I might think of more when I sit down to try to think of all the old titles over the years, that or comb through a few dozen backup dvds/cds that have all the emulation programs found over the years. Overall just follow what was done with Jungler, grab the obscure games so they really catch the attention as I'd be more likely to look at a game like Jungler (which I never played in the arcades) than some game that was everywhere like Marble Madness.

Also how about taking the technology from XBLA Pinball Fx & put that in. I'd love to see some pinball tournaments going on in the Game Room. Even if the pinball games are new & not classics, I think that they'd add a lot of activity in the Game Room from a lot of people like me who always enjoy going back to some pinball game to unwind. From what I've seen at the opening of Game Room & after hitting up the demo of every game, I love the possibilities of Game Room even though I'll wait til next week to see what pops up there.

Lastly, really liking the props of the Game Room themes & suggest something else for the game room props... skeeball.    

" arcade version of Splatterhouse,"

I want to see Galaga 3 and Galaga 88.  Hell, also give me Galaga and I'll have fun, even though I already have Galaga for XBLA and a lot of other systems.  
I'd also like the Star Wars arcade games.  Maybe Tron. 

Zookeeper! 
 
(Maybe I should clarify.  I'm talking the arcade classic, not the crummy GBA puzzle game.)

Well as fun as the classics are, I wouldn't mind seeing what they do once they get into more recent titles. I'd LOVE to play a ranked version of Metal Slug, for example. Oh man, and Metal Slug boss challenges, that would also be dope. 
 
in terms of older material, I think it goes without saying that some old school Midway/Williams shit would be -awesome-. Rampage, or Defender, or Joust would be sweet. Or Smash TV. Gotta get that in there at some point.  
 
And yeah I'm liking people's idea of putting in the Star Wars vector game. That would be sweet. Also Battlezone. Battlezone more than anything please.

I'd be interested in seeing a bunch of C64 titles like Kikstart II, International Karate+, Ikari Warriors, 4x4 Offroad Racing, etc.
 
Hopefully they'll add more recent games too as I'm not really interested in the really old titles they have now. Those Atari games sure are primitive.

...Xenophobe...Splatterhouse...

Problem with a lot of the games i'd like to see, such as Star Wars mentioned is i'm sure they still have to go through some extra licensing to use them (at least as far as i know).
I want to see APB, Rampage, Spy Hunter. A lot of these games though i just remember playing and don't remember if they're great or if i want them for nostalia...some of them don't hold up so well.
 
As far as my thoughts on GameRoom i think a lot of it could be done better...mainly i have a problem with the tokens / one time buy ins. i think you should use tokens to play ranked games and use MS Points to buy tokens. makes more sense to me. 50 cents is way too much for what yer getting out of some of these games for a one time play through and i'm only assuming that playthrough gets you into a ranked game, i don't even know but it sure as hell better not just buy you 10mins.

I want Strider and Zaxxon.

I want to see newer arcade titles, like the TMNT from back in the day. 
 
More importantly I'd like to see an online (via browser) tracking of Game Room stats.

splatter house arcade version, the simpsons arcade game, that X men arcade game where you could play 6 players and dragons lair.