King of Prussia Ski Club seems to be the big one.
I've participated in a few different clubs. Have only actually been a paid member of the Wissahickon Ski Club. They have their own ski hill with T-bar just outside of the city which is complete with a chalet for meetings. I wouldn't argue with you if you get the idea that they are a hoity-toity club. One must be sponsored by a member to join.
If you are young look into PFR meet-up group - they are an informal group of 20, 30 and 40 somethings with a small handful in their 50's. Nothing else in the city like them, Philly Trips & Travel and Main Line Ski & Social Club tried.