I would think that the Westin on North Michigan Avenue and East Delaware Place (opposite the Hancock Center) would be ideal for your purposes. It is very well located; close to shopping, dining and the lakefront and it is well served by public transportation and, of course, taxis. Some museums and attractions are within walking distance; others would involve a bus, cab or train (elevated train or subway) ride. FWIW, this Westin is one block south of the Drake.

Let me point out that I have not stayed in any of the Chicago Starwood properties in a number of years; my recommendation is based strictly upon location and ease of getting around. I will add that the W Chicago City Center (at 172 West Adams Street in the "Loop") would be the closest to the Blue Line rapid transit that serves O'Hare airport but its location is better suited to business travelers. To my mind, you would be better off at the Westin Michigan Avenue; I guess my second choice, based upon location, would be the Westin Chicago River North.