I love Chicago. But if you are looking for a city that is a lot easier to navigate, Minneapolis/St. Paul is a great place to visit. I think it has a more laid back vibe than a lot of Cities.
Como Park has a small zoo, botanical gardens, and Japanese gardens. All free. Minnehaha Falls is beautiful. There are some quaint little neighborhoods in the Chain of Lakes area. The Walker Art Museum and sculpture garden are great. There are great theaters with a lot of off-Broadway type shows. The Guthrie Theater is award winning. There are some nice museums--science, history, Old Mill, American Swedish Institute. There are all kinds of live music venues. You can take a tour of the caves that were used by gangsters during Prohibition. Grand Ave. in St. Paul is lots of fun to wander around (with a great ice cream shop). St. Paul Saints minor league baseball games are really fun. Twins games are fun. There are great restaurants! The Mall of America seems to be everyone's go-to place to visit. I would skip it. Personally I hate it. There are lots of festivals and music series held up there in the summer too. Stillwater is a suburb that is really cool. There are lots of antique shops and fun shops. A lot of the other suburbs have neat atmospheres.
Do a search for vacation homes to rent. My aunt is going to The Cities (as Minnesotans refer to the area) for a reunion with college friends. They are planning to rent a home on one of the lakes. A lot of people who own the old homes (century old) will rent out rooms like a B&B for pretty reasonable prices.
If you drive up, consider stopping in Lanesboro (couple of hours south) to spend the night. They have lots of really nice B&Bs. They have a quaint downtown and great bike trails. There are places to rent bikes.
Another cool drive is to follow the Mississippi through Red Wing, Lake City and other little towns up to The Cities.
If you fly in you will want to rent a car.