We went last year, to the 3rd party (August 31 I believe). It was our last (7th) night at WDW, and we were dragging our feet! We loved the parade but the only rides we did were Haunted Mansion and Splash Mountain (boyfriend’s favorite). We did 2-3 treat trails (lines were long) and skipped the Hocus Pocus show because I was just too tired. We had some AK planned for the following morning, plus our flight.
Personally, I would feel like I didn’t get my money’s worth for the party if I skipped the actual party stuff to ride rides. Especially going in August with relatively low crowds (for regular park days - our party experience was crowded but certainly not unbearable!)