Last time we were there the beach beds were for members only but from photos I have seen that may have changed (last time I went was May '08). Besides that there is a members "lounge" I think it may have drinks and a few other things and only members can rent the boat they have to rent. No big deal really. I had an awesome time without being a member.
When we were there a few weeks ago, there was very little space reserved just for members. There was a bar area on thebeach and maybe 4 beds about 50x50 feet nothing compared to what else is for all of us.