Try the Grange City Tower Hill. Parking is fairly cheap.
Id take the Grange Tower Bridge or Apex over it (all within 300 yards of one another). I tend to use all 3 most months, Apex first choice, Tower Bridge second, City 3rd. Must have spent 50 nights in them in the last year. Ideal for my office and quiet even during the week, but businesslike and not somewhere I would want to take my wife on her Birthday.
All subjective in the end mind.

The Hilton there also is good, but modern and cold but great roof bar!