I agree with magmax on all counts, and would only add that, to me, the main difference between the Imperial and the Bristol (about three blocks apart, on opposite sides of the same street) is that the rooms at the Imperial are decorated in an over-the-top rococo splendor, while the Bristol is more restrained (but still luxurious feeling). For that reason (and because of the across from the Staatsoper location) I've always stayed at the Bristol. If you search in the Starwood forum, I think you'll find some good reports about Platinum upgrades, including at least one Plat who was placed in the Prince of Wales Suite