There are few Places in Alamut valley where you can spend a night and do some activities next day. But there are houses to rent in almost every village.
Here i recommend some hostel which you can spend quite a memorable night.
My house in the valley; i have got two house with acommodation to rent.
No.1 My house in rice farm where there is not a lot of people around, with a nice garden in front of it, possible to barbeque aroud it, very nice view of lambesar castle and the valley and most importantly i can be with you sometimes to talk and plan!
Some people feel that it might be interesting to spend a night or two in a house living with people of the valley and taste the life they live. There are also plenty options to experience this!