We haven't been yet but have booked an apartment through London Connection. They're US-based but manage apartments over there. So far they've been accommodating and easy to work with and they even arrange car pickup at the airport if you want (for a fee). We picked a place in S. Kensington.

We rented an apartment in Covent Garden - 7 Dials neighborhood

We rented an apartment from Stay City. It was on the south side, near Tate Modern. There are a ton of what they call 'self-catering' apartments in London. It'll be the best accommodation for 5, and you can cook meals, make sandwiches for picnics, etc.

Citadines has an apartment hotel we've considered in the past but not used.

We will be in London for Thanksgiving holidays. We are a family of 5--please share recommendations for apartment hotels or other suggestions for us to stay. Would like to be close to typical tourist must see places vs on outskirts or locations less central. Our kids are 11, 7 and 3. Thanks!