Castle Crashers isn't a bad idea, albeit kinda dumbed down. Any Phantasy Star Online game that has split screen (Gamecube or Xbox one, for example.)
Honestly games like Dynasty Warriors aren't a bad bed. Most are two player I think (I only play the Dynasty Warriors: Gundam series) but Strikeforce is supposed to be 4-player split screen. Grab some demos on Xbox live and PSN and dip your toes in the water a bit, y'know?
My friends and I are always on the hunt for games like these and a lot of the stuff I've suggested kinda eases that desire a bit y'know?