Well the Hyatt Pier 66 is not on the beach but on the Intracoastal. The Marriott Harbor Beach is right on the beach but is not exactly quiet - lots of families with children.
There is a brand new St Regis that just opened but might be a bit pricey. Friends on Flyertalk seem to all love the Westin Diplomat but that might be a bit far for you since it's in Hollywood, FL.
