I was thinking about picking up a 3DS XL this weekend. Wanted to know if there are any good games for it at all.
Quite a few, depending on your tastes:
Super Mario 3D Land is one of the better Mario games in recent history
Fire Emblem: Awakening is a fantastic, time-sucking turn-based strategy/RPG game
Luigi's Mansion has been received very positively
If you are looking for some new takes on classic games you have Legend of Zelda: Ocarina of Time or Starfox available.
This is barely scratching the surface; I have left a bunch of things out, these are just what sprang to mind immediately. There are a TON of great games on the 3DS; really a solid pickup as you are likely to find something that fits what you are looking for.
As others have said, Fire Emblem is a fantastic time sink, NSMB2 is meant to be pretty good (heard nothing but good things from my partner who's playing it along with others). Also, if you're a fan of pokémon, or just enjoy the games, then you've got X & Y coming out at some point, but all the prior ones as well, Black & White as well as their continuations.
More titles are being thrown onto the download market as well, so things are moving on and of course you can still play any old DS games on the XL as well.
Fire emblem is the best game I've played since Dark Souls. Super Mario 3D land is my favorite mario game since Super Mario World, Monster Hunter is monster hunter for better or for worse.
And as mentioned elsewhere, you've got animal crossing, pokemon, the new link to the past, yoshi's island 2, and no doubt a slew of other games since this big 3DS push has really payed off for the 3DS. It's a great time to own one or at least be thinking about it.