here are a few that i had a search for that are cheaper and in decent locations! Depends on really your budget!
purplehotel London (looks nice http://www.hoteldirect.co.uk/webapp/hoteldirect/servlet/HDViewPage?web=yes&purpose=hotel&hotelid=729&city=London¤cy=gbp)
Park Plaza Riverbank London, Albert Embankment, Waterloo, SE1 7TJ
http://www.hoteldirect.co.uk/webapp/hoteldirect/servlet/HDViewPage?web=yes&purpose=hotel&hotelid=524&city=London¤cy=gbp
Norfolk Towers - 34 Norfolk Place, Hyde Park, W2 1QW
http://www.hoteldirect.co.uk/webapp/hoteldirect/servlet/HDViewPage?web=yes&purpose=hotel&hotelid=138&city=London¤cy=gbp
Holiday Inn Hammersmith, 120-124 King Street, Hammersmith, W6 0QU
http://www.hoteldirect.co.uk/webapp/hoteldirect/servlet/HDViewPage?web=yes&purpose=hotel&hotelid=97&city=London¤cy=gbp
Royal Eagle Hotel, 26-30 Craven Road, Paddington, W2 3WB
http://www.hoteldirect.co.uk/webapp/hoteldirect/servlet/HDViewPage?web=yes&purpose=hotel&hotelid=543&city=London¤cy=gbp
Troy Hotel, 68 -70 Queensborough Terrace, Bayswater, Bayswater, W2 3SH
http://www.hoteldirect.co.uk/webapp/hoteldirect/servlet/HDViewPage?web=yes&purpose=hotel&hotelid=542&city=London¤cy=gbp
Ramada Encore, 4 Portal Way, Acton, W3 6RT
http://www.hoteldirect.co.uk/webapp/hoteldirect/servlet/HDViewPage?web=yes&purpose=hotel&hotelid=394&city=London¤cy=gbp
Burns Hotel, 18-26 Barkston Gardens, Kensington, Kensington, SW5 0EN
http://www.hoteldirect.co.uk/webapp/hoteldirect/servlet/HDViewPage?web=yes&purpose=hotel&hotelid=406&city=London¤cy=gbp
Astor Court, 20 Hallam Street, Central London, W1W 6JQ
http://www.hoteldirect.co.uk/webapp/hoteldirect/servlet/HDViewPage?web=yes&purpose=hotel&hotelid=446&city=London¤cy=gbp
There are quite a few others but that just might give you an idea of the best places to look for and prices etc
id say you want to make sure your close to an underground station otherwise its to hard for you to get around!
Any where on the central, victoria, northern or circle line would be good!