iqs. London is large, very large, no Hotel is going to be in walking distance of more than a few of the sights that you might want to visit.
London has it's own Tourist Board and there are organised Tour Buses, some open topped, that give a Conducted Tour of the City with a recorded commentary available. I would suggest one of these for your first day and you could then decide on any other sites that you might wish to visit as a spin off from that.
An Hotel that close to the Tour Bus Route would be a good move. Contact london's Tourist Board for more information.