I've taken groups of teens twice. Both times, there were kids who had never been.
My plan was to make a list of a few "non-negotiable" things we would all do as a group each day. It could be specific rides you'll all go on together, shows, parades, fireworks....whatever you think they NEED to do, or will be a memorable or fun experience to all have together.
The last time I took kids, we did fireworks at DL one night and World of Color at DCA the next night. We rode the Matterhorn, Indy and Pirates as a big group, and then they forced me to ride Tower of Terror with them. You could also all plan a meal to eat together as a group each day.
The rest of the time, I let them split up into groups and have some "free time." We met up every three hours. That seemed like the right amount of time: enough time to get several rides in, even if the lines are long; but so much time I felt like they were running wild. I let them parkhop if they wanted, but they needed to text me who they were with and when they were leaving one park and going to the other.
I found out that there were kids who had been many, many times. They all made sure the "newbies" got to see and do the fun stuff. Honestly, it was fun to watch how excited they were to show the other kids things they knew and loved.
Also, you may want to ask each kid what the top item on their "to-do" list is, and make sure to do them all!
Hope it helps! It's so fun to watch teenagers get carried away with the joy and magic. They still talk about it, even almost 3 years later.
You will have a blast!