The Clift is an Ian Schrager-Phillipe Starck re-do of a classic San Frnacisco hotel which was one of the city's finest from the 1920s. It was especially renowned for its majestic Redwood Room, decorated with large prints by Gustav Klimt. The man who owned the Clift was nototious in the latter '60s and 70's for banning men with long hair from the Redwood Room. In the '80s it was taken over and upgraded by Four Seasons, who operated it until they gave up management in order to open their new-construction hotel on Market Street.
The location is perfect if you're going to see theatre, as the Curran and Geary theatres are essentially next door, in the same block. Union Square is just another block further down Geary Street.
Close to your price range, another alternative to consider is the Omni, which is at the corner of California and Mongomery Streets (and just a block or so down from the MO). While not in the very middle of the shopping/theatre area, it is just a few blocks away, and it is also an easy walk to Chinatown, North Beach. Nice rooms, excellent, personalized service. Good seafood restaurants (Tadich Grill - historical, and Aqua - modern) are just another block down California St.
For your night at the MO, consider getting one of the "two-bridge" rooms, with views of both the Golden Gate and bay Bridges , or alternatively, one of the Bay Bridge view rooms with a glassed in soaking tub