Mall of American in Minneapolis. Huge and fun for everyone. Also a little bit of baseball to it. A red chair is bolted to the wall above the Log Chute. The old stadium used to sit in the same spot and this chair is the farthest homerun hit. You can also find Home plate in the floor of the mall. We never found home but the chair is cool to see. Also the mall is so big it's like an amusement park.
Last summer we did the Rockies while the Brewers were there. Our family especially liked Red Rocks Ampitheatre and the nearby hikes in the foothills around Denver.
I will be following this thread, as we are hoping to hit a Twins game in July or August.