From the eShop you should also check out Attack of the Friday Monsters, Crimson Shroud and Phoenix Wright Dual Destinies. Of course Fire Emblem and Zelda are musts.
Plus you have the whole DS catalogue you can pick up for super cheap. Chrono Trigger, The World Ends With You, 999, Ace Attorney, Dragon Quest IX, Infinite Space, Castlevania Dawn of Sorrow and of course Ghost Trick.
The only game you'll really need is Hotel Dusk, though.