lanfan,
Thanks for the suggestions. DD4.5's preschool teacher gave me a Mindware catalogue with lots of great puzzles and games:
www.mindwareonline.com
I sent copies to the grandparents for Christmas gift ideas. I also picked up a game at Target called Castle Logix made by Smart Games. It was a hit.

This discussion has triggered me to rethink my plans for DD4.5. I may look at having her do a compressed Kindergarten year at a private school from Jan-May in order to have her start 1st grade in the fall. This may alleviate some of the problems we're having with our older daughter.