I’ve looked at this question recently in several European cities. Speaking primarily to Hilton (as that is where the majority of hotel points reside these days), it is often better to look at two base rooms vs one large room. To pick an example on a random 2 night stay in july using the first hotel Hilton lists for London, the Trafalgar St James (Curio) wants 95k / night and has two rooms available. Each can hold 2 people. Go to three and they want 469k / night. That isn’t a crazy suite either, it’s the family king vs a normal queen. Size goes from 28 sqm to 35 sqm. You will get way more space from two rooms.

Also, to be clear, I am not recommending the St James. It just happened to be the first one Hilton showed.

best of luck