I totally forgot about Castle Crashers.. that is really fun to play (the best part is the pooping, running deer). It isn't a very in-depth game, but it's fun if you don't have a whole lot of time, don't want to get super involved, or just feel like something light-hearted and amusing. And it isn't split-screen! Split-screens are evil.
So...feedback:
I glanced at these games and thought:
Awesomenauts = Donkey Kong
Towerfall = Zelda
Tried Fable 3 instead. Couch-coop my ass. I was basically a tag along. I literally had to stand there and watch the Prince get cool shit, even make out with chicks. Boo. That being said, if your girlfriend doesn't actually want to play video games but just wants to sit next to you and feel sorta like she's doing something with you, this is your game.