^^wow those are great tips Drummerally!^^
I've been in charge of many, many trips of high schoolers, mostly in the 80 - 120 person range. I've never taken a group to Disney, but I think some of the following would apply to any overnight trip:
I always had the "Big 3." Three rules that if broken, meant an immediate trip home/ to the most boring trip of your life. The Big 3 usually included things like
being found out of your room past curfew with out chaperone permission, damaging property that belonged to someone other than yourself,
being more than 20 minutes late to "check in time" (where you check in while at the parks, etc, so we know you are still alive)
or anything that involved breaking a law.
I'm sure you have them under control, but it always helped me to have the big 3 and really emphasize them, so that they knew that there were clear boundaries. I told them it was like the foul lines on a baseball field - they had some room to move around inside the field, but if they went foul they were out.
Cheesy I know, but it always worked for me!