I wanted to report back on our experience at Tuesday's party, in the hope I may be able help anyone who is going in the coming weeks (as so many helped me).
Firstly, I loved the party. I had never been to a special event at
Disneyland and I am so glad we took the chance on this one. I don't like to get too "compare happy" about WDW vs. DLR, as I appreciate both. But, boy, was this better than the WDW Halloween parties I have attended. Crowds felt totally manageable and we were able to do everything we wanted without killing ourselves. I agree with some previous posters that this party had less "atmosphere" than one might expect, but that wasn't a big deal for us.
So we focused on characters, treat trails, and the parade. We also rode several rides and did the Villains Grove walk-through. Thoughts:
Check In
We bypassed the winding line at the front gate and went to Blue Sky Cellar, thanks to the tips here. We went in around 4:45 and were in and out in about three minutes.
Treat Trails
Wow! These were so much more fun than we were used to at WDW. The trails are long and have stop after stop where they were practically throwing candy and snacks at us. We got SO MUCH candy it was ridiculous. We tried nine of the ten trails. I enjoyed the villain trails - some were more fun than others, but in all cases I liked that it was a little something different. I interacted with Maleficent and with Oogie Boogie and both made me laugh. The Mad Hatter had a big crowd and was also very entertaining. (His treat trail also had so many, many stops!) I did/redid all five villain treat trails from 10:00-10:45 and walked right through all of them. Earlier in the night there had been longer lines, especially for Oogie Boogie.
Villains Grove
I went there last, around 10:45. It was practically empty and I could go at my own pace. I'll admit that my pace was pretty quick because, although I'm glad I checked it out, it didn't really make much of an impact on me. A couple of sections were fun but in general I thought "Okay, cool" and then immediately forgot about it.
Parade
I had no trouble finding a great spot in Hollywood Land literally as the parade rounded the corner. But that was just me (my son is anti parade). If you had more people you wouldn't want to push it that late - although 15 or 20 minutes before would probably work. Parade was short and sweet, which I liked, and had all the Halloween highlights I wanted.
Rides
Logically, and as others have said, ride lines got shorter through out the night. But they were never really that long. We walked on Incredicoaster twice, Toy Story was about 15-20 minutes, walked on the fun wheel, and walked on Guardians at 7:45. We also walked on Goofy twice during WoC and then stayed for three rounds of the swings without getting off. Emotional Whirlwind closes during WoC. So we timed it and walked right in when it reopened. (I wanted to try it but it loads so slowllllly that it always had a a bit of a line before that.) We didn't ride anything in Cars Land.
Characters
Okay, so the characters were my main reason for attending. Before the party I had been through all stages of emotions, from excitement at all the characters to stress about how patchy the attendance of the characters seems to be. To my great joy we had all but one of the characters we wanted show up! I thought I would list the specific from our night about times/crowds. Of course, all of that could change for any other party...but I know I was starved for specifics and maybe some of it will stay consistent.
Villains
We got in line around 5:30 for the villains and were about fourth or fifth. The animal villains came out at 6:00. Initially it was only Prince John and the Big Bad Wolf, but as we met the wolf, the Sheriff of Nottingham came out. (I jumped up and down, which pleased my 13-year-old so to no end, as you can imagine.) We immediately got back in line and it timed out great - we were again about fourth in line when the human villains came out at 6:30. Frollo was missing and replaced by the Evil Queen...but we had met Frollo over at Disneyland earlier in the day, in a spot of luck. From what I saw during the night, as we passed by, the line seemed consistently about 30 minutes long.
Pixar
Next we went to meet Carl but we arrived just as his set ended. Starting off, Woody and Bo met on the hours and Carl and Russell met at 6:30 and then just Carl on the subsequent half hours. HOWEVER, that changed later. This meet shuts down for WoC and after WoC it was Woody and Bo at 9:30/10:30 and Carl at 10:00.
We also met toy soldiers roaming down by Toy Story. That was cool because a group of three were meeting/posing and I had never seen more than two together before.
Kim/Ron
Kim Possible was not at the party. Luckily, I knew this was typical and I expected it. Ron was silly and lots of fun and had nobody at his meet. I do not know when he takes breaks but we met him at about 7:20.
Loki
I had wondered if Loki would be hard to find but he was not. He was roaming near the Hyperion and GotG and we saw him several times. We met him at 7:30 and saw him again several times later. In fact, as I made my villain treat trail rounds at about 10:30, I noticed him standing back by the Hollywood Lounge, in the dark, just standing there alone, looking supremely and appropriately bored. He was great.
Star-Lord/Gamora
Star-Lord was meeting on the hour and Gamora on the half hour. We left the area after riding GotG so I don't know if that changed up later.
Blue Fairy/Pinocchio
When we came by before the parade, the Blue Fairy was meeting on the hour and Snow White/Dopey on the half hour. They stopped their meet during the parade. Just after the parade, at 8:45, the Blue Fairy and Pinocchio came back out. I had sat on the fountain right near where I knew they would be (having seen them earlier) and was second in line.
Afternoon Friends
Chip and Dale met on the hour and Don Karnage on the half hour (no Baloo at our party). They took a break during the parade and then switched: Chip and Dale at 8:30, Don Karnage at 9:00, etc.
Mickey and Minnie
They had the longest line consistently from what I saw. However, I walked by on my way out of the party after doing Villains Grove, at like 10:55. Their line was at least half an hour long and I saw no signs that it had been cut off.
Sorry this was so long but I hope it might be helpful for some of the other character nuts out there.