We stayed few nights in Whispering Palms hotel on our way back from Ella to Colombo. Despite being the rainy monsoon season on the West / South West coast, we had excellent weather. The sea is very rough though in this season and was very tricky to get in. Luckily the hotel has a nice swimming pool right on the beach, with plenty of sun loungers around it.
When we were in hotel, it was very quite, due to low season (monsoon). Has the advantage that breakfast every morning was cooked fresh to our liking. Rooms in hotel are ok, a bit limited in decoration, and looks rather basic. Beds are comfortable and bathroom is large and decent, good rain shower.
When staying in Bentota area one has to realize that all hotels are in a long strip and along a road in one line. So if you want to go somewhere, best is to take a tuk tuk to Aluthgama, where you have more like a little town with shops and so on. There are restaurants alongside the main road, it is just a very busy road and not really nice to walk along.