As a member of PCA leadership I am a bit biased.
* 10% discount at the dealer parts counter
* Free Panorama mag (soon to be run by a former Excellence editor)
* A resource for quality local services like repair shops, paint and detail, top installers, race prep, restorations etc.
*Car meets
* historic racing and car museum tours
* group canyon carving
* well established performance driving program including AX, DE, TT and club racing.
Every region has a little different culture and focus, and within each region are groups with a common interest. Some will get together and have an engine pulling or IMS upgrade party while others will spend a day doing concours prep. The wild eyed canyon carvers will take a run after a PCA breakfast and hopefully not get arrested. The track guys will be swapping stories about their latest car setup and tires. The socialites will be planning a gentle tour to the wine country.
As with most things, the PCA is not for everybody and the quality of your experience is often what you make it to be. Is it worth $46/yr? I think it is.