I have a couple of observations for you, one suggestion, and a one or two hidden gems (depending on how you count them).
Observation 1: I think you will understand what I mean by this because you have been there, but the biggest difference between WDW and Six Flags and the like is that WDW is a theme park and the other parks are amusement parks. It is difficult for people to truly appreciate how much difference this makes until they get there, and some people won't care about it even after they do. For some people though, it will change their perspective on what makes a ride a must-do to them, so I would be prepared for some changes to the must-do activities after you arrive.
Observation 2: Iconic rides like Splash, Big Thunder Mountain Railroad, etc., are iconic for a reason; most people rate them highly. Many of the not-quite-such-a-headliner attractions are lesser because the ratings are more divisive -- it's not that everyone rates them a 6/10, it's that some people rate them a 8/10 and some people could care less if they never did it again. For these, you may not be able to predict well in advance if you'll like them or not, so don't be afraid to try something (time permitting) that only a minority of your group is interested in. This is how you will find the things that are hidden gems to your group.
Suggestion: I did see your post for preference on the MK above, but for hopping MK is often touted as the best to hop to because it is open at least a couple of hours later than all the other parks. Epcot can also be good as the World Showcase is easily consumed in small pieces, so only having a couple of hours is fine. It's quite possible that you will find you have not anticipated reactions in the other parks well, and people will either spend the entire day there that you hadn't planned or else everyone is finished in the early afternoon. My suggestion, if finances allow, would be to do Epcot and MK (in either order) as part of your first two days. Then you will have enough experience with these parks that if you find yourself at AK or DHS and are just "done", but feel like you may have more to do in Epcot or MK, you can consider adding on park hopping and spend some extra time at MK or Epcot. Hopping is an extra $64 flat fee per ticket no matter when you add it on.
Hidden gem(s): When I saw the ages of the kids, the one thing I thought of immediately is that my kids would tell them to make sure not to miss the Agent P World Showcase Adventure. We were fortunate enough to enjoy a bonus trip this year in addition to our planned one in August, and my kids (14, 11, 7) spent a good amount of time on this and didn't remotely think it should cut into the amount of time that would be allotted to it in August. This despite the fact that they have played it on multiple days, for at least an hour a day, when we were there in 2009, 2011, and 2013. It's fun for all ages, but your group of kids are in the exact target age range. Sorcerers of the Magic Kingdom in the MK is similar but very different; there is a trading card aspect and whole other atmosphere around that one. My kids love them both (with a big, big, big edge to Agent P), but they are not the same. Wilderness Explorers in the AK is a very distant cousin in this group, but it has by far the biggest differences from the other two -- more education focused rather than entertainment, no cool technology, etc. I mention it here only because you will see it referenced if you look up information on the other two. For your particular group I would rate Agent P as absolutely not to be missed, and in the MK I would try Sorcerers if time allows but not worry too much about it if the day there is too crowded with other things.
