Here's what I've got:
Millenium Bailey's or Millenium Gloucester -- GBP 72 no breakfast
Hilton Docklands -- GBP 68 std./89 dlx. no breakfast
Hilton Olympia -- GBP 75 std. no breakfast, GBP 100 dlx. w/breakfast.
Hilton Kensington -- GBP 75 std. no breakfast, 100 exec. dbl. w/breakfast.
Radisson Vanderbilt -- GBP 80 no breakfast
Royal Horseguards -- GBP 94 w/breakfast
My inherent cheapness will prevent me from going much higher that that, esp. as I'm going with a no-maintenance college buddy who probably expects that we'll stay in a hostel or something. If any of these places have esp. good breakfasts, that'd be interesting to know, as we can definitely eat enough to make it worth it