I second the Flint Hills Children's Festival. Very fun. Lots of great shows, very inexpensive if not free. And Grand Old Days (as some of us native St. Paulites still like to call it, though it's just one day).
The Bakken Museum of Electricity is also fun, and it's right on Lake Calhoun in Uptown Mpls, a nice little area.
Bakken Museum Also a fun children's museum downtown st. paul. Your 7yo may be aging out of some of the stuff:
MN Children's Museum Also, MN Zoo. Seuss on the Loose will be happening when you're here:
MN Zoo Or Como Zoo is free:
Como Zoo and Conservatory
