What do you mean by age restricted? If you are talking about wanting a park full of young people, you are SOL. If you mean you have an older rig, the very nicest parks (Outdoor Resorts and Motorcoach Country Club) are not age restricted, but the older rigs there are mostly Prevosts and Newells. A 25 year old entry level gas rig with no slides and faded paint isn't going to be welcomed. Also, cost will be high. Lots will be from $50K up to $500K. Rentals will run $2000 a month and up.
I disagree wholeheartedly with Barbara about little to do in the Palm Springs area. There is a wonderful zoo, casinos, more independent restaurants then you can eat at in a lifetime. The casinos and the McCallum Theater have national entertainment acts almost daily. The Coachella Music festival is a world wide destination. There is Polo every weekend that is free to attend and a hoot. The Palm Springs tram is spectacular. There is both the Thursday night street fest and the College of the Desert vendors of shopping every week as well as many small shops, a large mall and all the outlet shops that are just over the hill. There are art galleries, Modernism Week and Sunnylands for the culturally leaning. There are mountain trails, desert trails and city trails for biking and hiking. And yes, there is some tennis and golf.