@Traveller:
Will take hints on good eShop games to try out or what classic (3)DS games to play.
It depends a lot on what you like. Pushmo and Crashmo from the eShop, for example, are really good puzzle games, but wouldn't be a very good purchase for someone who wasn't much of a fan of puzzle games.
The Golden Sun games, Dragon Quest games, and several others like Radiant Historia (Atlus in general is pretty good) are great role playing games. I think the original DS was probably the best RPG system we've seen this century.
Strategy games also tended to live more comfortably on the DS (and GBA). The Fire Emblem games and Advance Wars games probably top the list there, but there are plenty of others too. Ghost Recon was a turn based strategy 3DS launch title, and I thought it was a lot of fun.
Then there are the Nintendo specific games that are so well loved which you've already dipped into. Mario 3D Land, Mario Kart, Zelda, Star Fox, Kid Icarus, Paper Mario, Luigi's Mansion soon, etc. I also have high hopes for Lego City this March.
I find that I personally get the most mileage out of those 4 subsets of games on the 3DS (RPG, strategy, puzzle, and exclusives). I tend to prefer playing the other genres on other consoles more.