So, you're saying there are "girl" games????
I play my DS nightly...and I play a variety of things. We have something like 40 games...all of different platforms.
CrossworDS and Clubhouse Games are the two I play most often. Had them both for quite some time and they are good, relaxing games to go back to. I've been racing on Mario Kart DS lately, too.
Professor Layton is good if she likes logic problems mixed with puzzles. Animal Crossing for a game that never dies. Peggle is a good one, too. I have the Gardening Mama game, and I'm not impressed, but lots of people like it.
But, seriously, asking what games women will like is kind of a silly question. Maybe she would prefer shoot-em-up games to puzzles and relaxing stuff...who knows? We're all different you know.