TeeS,
Personally I like the Senegambia. I was last there a few months ago. The rooms are passable, the staff friendly, the food good, the gardens beautiful and the swimming pools nice.
Any of the good quality hotels in the resort areas are reasonable, and better than staying in Banjul itself.
One thing to watch out for if you're sending unescorted ladies there is that there are quite a few European women who visit the Gambia to meet the local chaps, many of whom are waiting to meet them in the local bars.
The weather at this time of the year is good and it's a nice place to spend a week away, even if scenically a bit unexciting. Most of the hotels can arrange visits to local villages, canoe trips, hippo viewing etc. Prices are not tgo high and the local beer (Julbrew) is passable. Hope the ladies have a good time