One series I would definitely recommend people to try is Rayman. Lately, they've been releasing amazing games, with Origins and Legends being two, great examples. I've played both, and loved each and every moment. Personally, I like Legends better, as it's got better overall graphics and more content, generally. Their handheld ones are pretty fun, too, but I don't think I've ever tried any for 3DS (not exactly sure if they'd ever released them, either, even though I should).
If you guys haven't attempted playing Legend of Zelda: Skyward Sword before, then you should definitely give it a go. Not sure about others, but in my opinion, this is one of the best games of this series; its story is very engaging, and art style is simply fantastic. When playing, you're going to feel as if you're actually a part of it (especially considering how the game utilizes WiiMote), and not just someone who's watching from a television screen. So far, I've completed Skyward Sword about four times, and am currently up to my fifth run. Maybe sixth. Regardless of how much I play, however, this game never seems to get boring.