Hi and welcome to the forum!
We're getting married at the Pier House June 26. We went down this past November to check out a few hotels and make our decision. They do have a small, private, topless private beach, but that is the area that is where the wedding ceremonies are held, so when there is a wedding, it is closed to sunbathers. They do have an additional adjoining private beach that is not topless, so there may be people on that during afternoon weddings.
Pier House is in Key West, but when we were there in November, the Pier House, itself, was very quiet and relaxing (even though it is on Duval Street), but the craziness/touristiness of Duval starts about a block away for anyone who wants it.