hi,
we were in paris and london last winter with 2 young kids (5,7). For Paris, we stayed in an apt. It's good cos there is more room for the kids, plus we did some cooking and laundry. Go to tripadvisor.com and there are so many to choose from. For london, we stayed in Premier Inn near Kings Cross. Its good cos they provide free beds for kids and kids eat free breakfast when adults pay. Many locations to choose from. It's not your fancy 5 star, but we found it clean and if you book early, sometimes you can get rooms at 50% off, which is a bargain for london. If booking B&Bs, make sure its good, cos some cheap ones are quite dingy, if you read reviews on tripadvisor.
mfalcon:given that this year london's hosting the Olympics, just wanted to get some thoughts if it is wise to visit uk in late may - early June? i m planning to visit london and Windsor. Windsor mainly for the castle n legoland.
ps: Olympics starts in later part of July