For RPG junkies, go look at the Tales games. I've played Tales of Symphonia, Tales of the Abyss, and Tales of Legendia, as well as about half of Tales of Phantasia, and they're all really fun. The battles handle almost like Smash Brothers, but with the exeption of Legendia and Phantasia (and pretty much all of the Tales games that were released before Symphonia) you play on a 3D battlefield, and it's really fast paced so it's good for the manic people out there. The stories are very compelling and draw you in, run you around a marathon course, and spit you back out feeling like you don't know what you just played, it's that good, and even I, the crossover writer who can predict a lot of plot twists, couldn't see these twists coming. As far as replayability, the game doesn't end when you beat the games. Load up a new game on your old file, buy some nifty extras like x2 experience, and go through the game again! Some things can only be accessed on your second playthrough like extra dungeons.
Yeah... you can tell I like the Tales games, huh? XD Tales of Symphonia is for the Gamecube, Abyss and Legendia are for the PS2, and there's a PSP game called Tales of the World: Radiant Mythology which has my inner crossover fangirl squeeing madly, because it has characters from every Tales game ever made in a new storyline.
Also: Super Mario Galaxy. Play it. It's awesome XD I just spend five hours yesterday playing it and my wrist was hurting.