Just got back from our trip and our second MHP last night

Had a better experience this time, mostly because we went to the Toon Town and Carnival pre-parties. We stood in line for Toon Town at 4:45, so went in with the first bunch of people, and we able to do all the treat trails and meet Horace and Clarabell with hardly any wait. It was nice seeing Toon Town so un-crowded, but as we were leaving around 5:30 the crowds were definitely picking up. We went to the Carnival pre-party and found it pretty un-crowded as well, and got to see the Dapper Dans up close on stage and met Woody with a tiny line. Vampire Pluto came out and walked around the carnival with his humorous handler and got into mischief here and there (vampire-biting people left and right), and invited kids to follow him around and dance with him. It was pretty awesome.
After those two places, we had MORE than enough candy for any sane family, so we didn't feel the need to do anymore treat trails, which freed the rest of the night on meeting characters my kids wanted to meet and riding the last rides of our trip (Pirates and Story Boats were walk-ons, but Peter Pan and Haunted Mansion had 30 min. waits still!). We chose not to watch fireworks or the parade because of the crowds. My kids got to meet Pirate Donald and Chip & Dale (at Zocalo Treat Trail) and Jack Sparrow (in front of the Columbia, who switched out about every hour with Peter, Wendy and Hook.
Jack Sparrow was definitely the highlight of the night and was HILARIOUS. The lady before me had a 3 month old baby, and when presented with meeting the infant, Jack circled him like it was a strange animal and he'd never seen such a thing. So funny! Hearing how rare Jack is on a usual basis, I would suggest anyone interested on meeting him ask the handler ahead of time on when the characters switch out, and plan to be in line at the right times. It saved us a lot of grief and time.
Finally, my 11 year old wanted to hunt down a Storm-Trooper. We had been circling Tomorrow-land off and on all night, with no luck. Finally, 10 minutes before party close, we saw THREE of them all at once in an a (by then) very cleared out tomorrow land! They were stomping around like bullies knocking people's candy bags around, and properly annoyed at being bothered by my son (they ARE villains after all) and refused to sign anything, but let my son take a picture with him (after my son used the "force" on one of them, as suggested by a handler. Apparently they usually deny even pictures!)
So after one un-fun Halloween night and one very fun one, I would suggest to definitely try to go to the pre-parties early on and get a few characters in and do the treat-trails to get the candy out of the way so the rest of the night you can focus on other things. All of the treat trails were ridiculously packed until around 9:30 or 10pm (on a 11pm close night). If I had known that the first night I would have waited to trick-or-treat till then. Even while crowded they moved along well, but I much preferred when the trails were loose and could easily keep walking than squished into a a slow line by a hundred people. Frontier-Land and New-Orleans were still the most packed areas, so we stayed out of there except to ride HMH and to go to the Stage-Door and Zocalo treat trails (which was really well decorated).
Anyway, sorry for the book!

I think we'll maybe try to come back for one night next year, maybe. The ambiance itself is too cool to miss, but hoping next year they'll temper the crowds a bit more.