My GF just got back from Hiroshima with a pile of DS games for me.
Right now I'm playing Nobunaga's Ambition DS 2, next up are Sim City Ds 2 and Dragon Quest 5 DS
Nobunaga's Ambition is great, I can't imagine playing it without the touch screen / dual screens. There are so many stats that I wouldn't bother checking if they weren't always available on the top screen and the stylus feels so much better for strategy games than a cursor (or even mouse)