Minnesota - our favorites are (1) Itasca State Park to see the headwaters of the Mississippi and (2) the North Shore of Lake Superior. Stop at some of the state parks and hike. Gooseberry is a favorite park. Walk from the water falls along the river to the lake. Follow the lake south for about two blocks. Another nice hike is in Tettagouche State Park to shovel point. Cascade State Park has a nice hike along the cascades; walk until you cross the river on a bridge. The hike along Temperance River has wonderfully carved features. All of these hikes along the North Shore of Lake Superior can be done by using the parking spaces along the highway. The hikes are all beautiful!
Of course, there is the Mall of America if you like large shopping venues. Don't miss the aquarium on the lower level of the Mall of America. That is a must see!