Two of my top faves (though I play PS3) are Bioshock 1 and 2. Both are awesome. Great if you like fantasy / sci fi kind of stuff. (If you like the Fallout games, you would probably like the Bioshock games.)
Currently I'm playing Tomb Raider Legend (picked up three games on one disc for a cheap price - I love the Tomb Raider games for all the puzzles and things like that), Mafia 2 (you might like that one), and Undead Nightmare (I LOVED Red Dead, though, I got very attached to the characters in that one - it's one of my all-time faves along with the Bioshock games. Undead Nightmare is very similar just with zombies, which is fun.) I thought LA Noire was great at first, but then I got pretty bored with it. I did eventually finish it, but didn't feel much about it at the end. I also liked Batman Arkham Asylum, once I got into it, which took a little perseverance. It really is a good game once you get the hang of it - I really liked the stealth part of the game, trying to figure out how to take down multiple enemies on the sly. Pretty cool. Didn't like Assassin's Creed, though, got really frustrated with that one for some reason.
Also, if you like racing games at all, I really like Wipeout HD. Super fun to play on 2 player mode (and it's amazing if you have a 3D TV and glasses, but we play it both ways depending on our mood.) It's not a "geek out and play all night" kind of game, but it's great if you have people over and want to take turns racing or just want to play something for a half hour or whatever.