We are going to a wedding in Minneapolis (actually Sunfish Lake) in August. We have two kids who will be 4 years old and 8 months old and are looking for advice on kid friendly lodging and recreation options.
Sunfish Lake, where you are going, is actually a very exclusive suburb of St. Paul, where I would recommend you stay. St. Paul has an excellent children's museum and an excellent children's museum within walking distance of each other (for adults--you might want a stroller for your 4 year old. ) I would recommend staying either at the St. Paul Hotel (if you want to go first class--closest to the Science museum) or the Holiday Inn Town Square (which has been renovated in the past 4 or 5 years & should be OK, presumably less costly). Both have fast access to small but nice parks--the St. Paul Hotel fronts on Rice Park, and is flanked by the main library which has a great children's reading room and typically has puppet shows, magicians 7 the like on Saturdays or Sundays, I forget which. (It was being renovated back to Victorian glory when we left but I imagine they are done now.) Across Rice Park is the Ordway Theater, home to the St. Paul Chamber Orchestra (world-class), various other solo performers & touring Broadway shows in the adjacent McKnight theater. If the Hotel could find you a sitter (my bet is they are equipped for that) you might be able to escape for an evening. There is also a nice, fairly kid-friendly restaurant in the Old Post Office building on the other side of Rice Park--the restaurants in the St. Paul Hotel are very good but pretty ritzy & therefore not the best place for kids. The Science Museum is supposed to have a pretty good restuarant but I never got there. Your 4 year old will love it, though. The Holiday Inn is next to Town Square & Town Square Park, a very nice indoor green space; great for kids. There are a couple of food courts on the adjacent Skyway, which will take you to the Children's Museum--they mostly serve the workday crowd but my bet is that some of the places are open on the weekend. This is a good place to feed kids. My kids were past infancy when this museum was built but I seem to recall a room designed for infants' sensory experiences, as well as many other rooms appropriate for older children. There is(or was) a loud restaurant next to the Children's Museum called the Hearthrob Cafe--burgers & rock & roll--that would be good for kids. There are ethnic restaurants along that street, too, that might be kid-friendly.
Both these hotels are close to the Arena/Convention center where the Minnesota Wild hockey team & other miscellaneous sporting events (& shows like home & flower shows etc.) occur. There is also a nice downtown park--Harriet Island, I think it is called-- that might be accessible on foot from these hotels--I forget which bridge you have to cross--at most it would be a 5 minute drive. It is an island in the Mississippi & a great place for kids to watch the barges, etc. There is a nice, kid-friendly restaurant on a houseboat there, the name of which escapes me, that would be fun.
If you have a car, I would suggest Como Park, about a 10 minute drive. There is a wonderful small zoo you could do in half a day. Sparky the Seal does 2 shows a day on weekends & there is the usual burgers, etc. to feed your 4 year old. Next to the zoo is a wonderful glass arboretum(kind of like the one in Golden Gate Park) with a beautiful Japanese Garden adjacent. Lake Como is also a nice place to stroll & feed the ducks. You can rent paddle boats and there is a not-fancy restaurant in the boat house.
If you are there the last week in August, I strongly recommend staying long enough to take in the Minnesota State Fair--I would take the #5 bus from downtown or find out about satellite parking from the concierge because they get 100,000 people a day or so & parking there, particularly on weekends, is difficult. Your 4 year old will love it--I can tell you more about it if the dates work for you.
I am sure there are websites for all these places. The downtown Radisson is also a good hotel, if the others are booked. (If you are going during State Fair week, you will want to book soon.) We moved here from St. Paul about 9 months ago, and as you can probably tell, we miss it very much. In August it could get extremely hot, but bring sweaters for evening. And rain gear. It does rain in MN during the summer, unlike here.
This is an addendum to the message I sent earlier: I forgot to mention that, adjacent to the zoo in Como Park there is an area with very inexpensive rides for small children--mini-roller coasters, a small merry-go-round, airplanes and little cars to ride around in, and so forth. The 4 year old would love it. Mary Ann