Full disclosure: I have been to London oh, maybe a dozen times. But I have never stayed in a hotel – I always stay with friends. (Or else I wouldn’t be able to afford a visit to London.) So when friends ask me for advice on London hotels – especially affordable London hotels – I am at a loss. But for my friends A and N, I’ve done a little sleuthing (my usual – just google NYTimes travel section) and this one sounds good – excellent central location, although could be a tad noisy, and remarkably reasonable price – if the rooms really do start at $136. Dean Street Townhouse, 69-71 Dean Street, W1D; (44-207) 434-1775; deanstreettownhouse.com.
for more details see: http://travel.nytimes.com/2010/04/18/travel/18checkin.html (This same issue, which was on economical europe, may have some suggestions for paris – although I love the place we recommended to you there.)
Thanks for the hotel suggestion, will check out NY Times further!