Within a few blocks from 100 W. Wacker (is that the specific address?) there is the Westin River North and also the Renaissance Hotel. Both are nicer than the Amalfi in my opinion, but neither are truly "luxury" hotels. The finer hotels like the Peninsula, Ritz Carlton, Four Seasons and Park Hyatt are all closer to Water Tower Place and as you mentioned, Chicago Avenue.

A few other options nearby are the Hard Rock Hotel (which I like very much), the Hyatt Regency (not so much), and the Monaco Hotel (never visited).