My brother has Fantasy Life and he likes it. I don't have the spare time to put into that game but it interested me as well.
If you like Pokemon, grab Pokemon Shuffle from the eShop since it's free~ it's one of those match 3 puzzle games. There's also Pokemon Picross which more freemium than free, and Pokemon Rumble which got a bit repetitive for me but hey it's also free.
I liked Animal Crossing : New Leaf but I drifted away from that game and now I'm afraid to launch it in fear of my villagers all moving out
haha It's as casual as you want it, and real time multiplayer walking around other players' towns is fun. I still have the most hours played in ACNL out of all the games in my library.
The Phoenix Wright : Ace Attorney Trilogy is a good one if you haven't played the 3 games on the DS (Phoenix Wright: Ace Attorney, Justice For All, Trials and Tribulations.) As far as I know it's the same content as those three older DS games but with updated sprites. It's basically a visual novel but you have to poke around and talk to people to get the story to progress. Dual Destinies is the other 3DS title, but you might want to play Apollo Justice (DS), the Miles Edgeworth game(s) (DS), and then the Professor Layton crossover (3DS) before that Dual Destinies for the whole story.
I'm waiting for the Rhythm Heaven NA release but Theatrhythm Final Fantasy: Curtain Call is pretty good for my rhythm game fix. Apparently they worked hard to make it run and read input at 60 fps so it's playable. You can pick stylus or button input methods. There are a lot of DLC songs but the included library is sufficient if you don't want to spend more money.