This is the official tour on the boat called Chicago's First Lady, which departs from the Riverside Gardens two full flights of steep stairs below Michigan Avenue. Telephone for information on accessibility for disabled people. This boat is comfortable, with both inside and outside deck seating. On bright days, be sure use your sunscreen. There is a volunteer docent on board who will give you a fast lecture during the 90-minute tour. There is also a bar that sells cold drinks, coffee, alcoholic drinks, and snacks.
This tour starts by heading away from the lake and visits both branches of the Chicago River. The buildings are so amazing that even with the docent and the provided map in hand, it will seem to go by too quickly. There are more bridges than Paris, or so they say, and more high-priced real estate than you can imagine.
Likely a bit of a bore for children younger than 12, it is a fascinating tour for those who are older than that. The boat goes out on the lake very briefly, but doesn't enter the locks. The commercial tours from the Navy Pier spend a lot of time dealing with the lock, but likely are easier for disabled folks to board from the pier.
Chicago is such a classy city that you might find yourself feeling very "small town" when you go home.