I have a trip report in my signature about our day at the 24 hour event last year, but I'll do a quick summary since I think my experience can answer some questions from this thread.
We stayed for 24 hours. Overall, I believe this strategy works best:
-ride must dos, slow loaders, or popular rides in the morning
-the park didn't really get crowded last year until about 11 or noon
-it was very hot last year, so plan accordingly, we did wear costumes, but we made sure they could work well in the heat
-after we had lunch, we began our mid-day plan: watch all the shows and ride things like TTA. So we spent the whole hot afternoon in air conditioned sit down shows, MK has a lot. (COP, HOP, Philharmagic, Tiki Room, Country Bears, Monsters Inc), and not one of those shows had a very long line.
-we had a dinner ADR at Crystal Palace so we could have a break
-we made all of our FPs for after dinner, since I had heard that would be the busiest time
-so we walked onto BTMR and then got our FP seats for the Electrical Parade
-after the Electrical Parade we headed back to get into line for our must do characters: Hades and Meg
-so for the busiest time of the park day we were tucked safely and quietly back in the Storybook Circus land.
-we got to meet Hades and Meg about half an hour after they started to greet, by that time it was about 2:30 am so the park was empty
-we met several other villains and walked onto numerous rides along the way
-we ended the night with a ride on the carousel and then slowly walked out as the park closed.
I am going to use this strategy again this year (with a few tweaks) because it worked really well.
We don't have any ADRs this year, though I am still trying to find a bfast or lunch at BOG
We will be wearing 2 costumes this year, stepsisters and stepmother and then a costume change for night that I'm not sharing because it is going to be amazing
We started our FPs at 6 pm. We have Peter Pan, 7 Dwarves and then Wishes, I think the Wishes FP will help a ton with all the congestion
I hope they announce special characters soon, and I really hope they start them earlier than 2 am.