In the same boat, going 4 nights is May.
Booked 2 nights Novotel suits at the airport, place has some of the best rating among the Accor properties and price is not much different from normal Novotel. Location is good too, with airport/beach view and in front of the train station.
Then 2 nights Ibis Styles
Beaulieu Sur Mer. Area is very nice to relax and good location to do daytrip to Monaco. Reviews are also very good + free breakfast. Can report back if anyone is interested 
2 x 2 nights is to max the current promotion.