This is what a UK colleague sent me last year, when I was planning a trip there:

London can be a bit of a minefield when it comes to hotels – and be warned it isn’t a cheap city! You also have to be careful because if you go too cheap you will end up somewhere not nice – air conditioning isn’t standard either by the way here – very few people have it in their homes – some hotels have it but not others. Needless to say I rarely stay in a London hotel either because I live here but based on what I know here are some ideas:

http://www.citadines.com/en/uk/london/trafalgar_square/apartment_types/1-bedroom_premier.html

It is very central and safe, near a tube and plenty of places to eat and walk out to. I walk past it regularly so know the area. For London and being so central the price seems good to me.

http://www.regencyhouse-hotel.com/

A little further away from the centre but also a nice area and easy to get into the centre and near a tube – this area has a number of University of London colleges and has an academic air about it although in August there wont be many students about!

Let me know what you think – one area I would avoid is Paddington – I think a lot of the hotels round there cater for backpackers etc and are pretty shabby!