The Residence Inns at London Bridge and Tower Bridge (2 separate hotels) are small apartments with bookable double bed & then sofa bed in the small lounge/ studio part which is separate to the bedroom. Stayed before and pretty good value for a (near) central London property.

Paris is a harder one as I've looked many times and availability is patchy. The Courtyard Gare de Lyon has a points & cash rate for double + sleeper, and the Moxy Bastille has a paid rate which isn't too bad (but reviews are very average).