My input that hasn't already been mentioned:
Arc Rise Fantasia (fun and decent JRPG but turn off voices, the dub is AWFUL!)
Boy and his blob (very fun, not terribly difficult, though)
Both Super Mario Galaxies are awesome
Kirby Return to dreamland is a ton of fun, as long as you're willing to put in the $50 to buy it. (the first half isn't that hard, but the difficulty picks up a bit in the second half)
Kirby Epic Yarn isn't difficult, but is a lot of fun.
The pikmin remakes are pretty good.
Kirby's dream collection is pretty awesome, it has a bunch of great classic kirby games.
Final fantasy Crystal Chronicles echoes of time is pretty awesome, don't let it's association with the godawful gamecube game make you ignore it.
Super Paper mario is great, too, but don't expect it to be like the other ones.
Wario land Shake it is a pretty cool 2d platformer. I could go on for hours, but I'm leaving it at that. How about you list games you think might be interesting, and we can weigh in on them.