Welcome to the 3DS family. My recommendations (and they've been mentioned already) are.
Mario Kart 7
Kid Icarus: Uprising
Pokemon X/Y
Luigi's Mansion 2
Super Mario 3D Land
Ocarina of Time 3D
If you've already played it on the Wii, then you may wish to give Donkey Kong Country Returns a miss as it's been said there isn't enough "New" in the game. But if you've not, then i recommend it. Brilliant platformer, great for the 3DS.
Animal Crossing New Leaf. This is one game that can be a hit and miss, but that depends on your mood for sim-style games. This one allows to to basically run the town as you want, creating your own town with many personal touches. Unfortunately, you can't go on a rampage against Tom Nook (oh i wish this was possible) but it's a damn fine game, and one that will keep you coming for a year for short daily/weekly visits to see events etc.
Future releases for 3DS, well it has to be A Link Between Worlds
And not forgetting the e-shop of course with the Virtual Console. On my 3DS, i have (and i recommend)
Oracle of Seasons/Ages
Links Awakening
Super Mario Land 1 and 2
Wario Land
I havn't ventured into other indie games yet, but i plan to soon enough.