Following Artoo's suggestions, I bought a DS last week. Since then, I've bought 3 games, MarioKartDS, The New Super Mario Bros, and just last night, Animal Crossing.
We decided we should have some kind of handheld for the trip to London coming up in a few weeks. Turns out, this is coming in handy for many other times: when the tv is being monopoloized for Corrie St., when the game cube is being using for the original Animal Crossing. Even in the car on the way to work!
I really like the New Mario Bros game. I beat really quickly, since I'm a mario wizard and all, but I'm liking going back in and replaying different levels to find the secrets. It's packed full of secret exits and warp pipes. Heck, you can even play as Luigi! Go Luigi! I think what makes this game so great is that it's a simple side scroller, so that makes the learning curve like 0-2 minutes, and that it takes all the things you loved from previous Mario games and throws those features in: like ground pounds, chain and rope climbing, even wall jumps.
The other games are fantastic as well. But I've yet to try out the multiplayer or WiFi (which I'm now calling NiFi). All the places I've taken my DS to try the wireless hasn't been successful: Alex's, Work, I even tried hacking into my neighbours wireless connection, but no luck so far.
I expect the MarioKart and AnimalCrossing games are a must for the multiplayer ability. Perhaps we'll buy another DS when the DS Lite comes out in June so that we can multiplayer it up easily and anywhere.