It may be worth your time to dig for some threads on the Christmas party. I can't speak for AH events from personal experience yet, but I can tell you that whether an MK holiday party is right for you really, really depends on what you want to get out of it. From the standpoint of getting to see special entertainment, a different parade, characters in special outfits, etc., it's great. However, if your priority is short lines for rides you will probably be disappointed by the Christmas party.
Meanwhile, reading this thread I'm wishing there were an MK AH during my trip...I'm excited for AK, but I wish I could do both! It'll be the last night of my trip; I'm planning to rope drop another park, take a nap, then close out the night with AK AH.