We stayed at the Park Tower, and loved it. Very nice well appointed room, good room service, and can't beat the location, especially if you like to shop. Harvey Nix is right across the street, and Harrods a block away. You are right in Knightsbridge -- good tube and bus connections around the city.

Only downside was when our taxi got stuck in traffic en route to the theater. In the end, it was quicker to get out and walk...