Nice. It's a great system. Good call on the DSL over the DSi.
My favourite DS games? Off the top of my head:
Final Fantasy IV DS;
Elite Beat Agents;
Brain Age;
Dragon Quest IV;
Professor Leyton;
The Legend of Zelda: Phantom Hourglass; and
Hotel Dusk: Room 215
(Oh, and Disgaea, but I already have it for PS2)