may i recommend, for those who live on the edge
http://london.ratestogo.com/.
wait a few weeks then book.
the trick is knowing that:
a) there is no shortage of hotels in london
b) the weekend 13th may to 15th may is not 'high season'
its just a recommendation, pick all suburbs because they're all central enough and have tube access or are £4 away by taxi. for people unused to lodon, when you use the site, have the tube map in another window.
the 'west end' is to draw a square tottenham court road down to charing cross and left to about green park then up to bond street then back accross. and zone one represents a walkable distance or a cheap cab ride.