The energy at Epcot is what is impossible to describe.
MK just didn't have the same energy, even with the DJs going on the 30th. Maybe it was there on the 31st. It was the same DJs so I'm guessing it was the same so that's what I'm basing my opinion on.
Plus, MK was open till 3:00 AM on the 30th, with EMH, where it closed at 1:00 on the 31st. So you had more time to stretch out and relax, so to speak, after fireworks on the 30th.
We slept in, moved to an Epcot resort and then headed over to Epcot for the day, took a nap and then spent the duration at Epcot. The crowds are part of the fun.
But no, even at 10, I wouldn't have wanted to take DGD. Not because she wouldn't have been any trouble or because the crowds were a problem but it would have distracted me. So do go sans kids if at all possible. It is totally different
The only place you have to pack "your patient panties" as I like to say, is in bathroom and drink lines. They are massive. Boys, girls, doesn't matter. Lines are long. Even inside restaurants. So you learn fast to go before you have to go. As long as you do that, it is manageable. And I clearly had no problem with finding enough to drink, I got plenty tipsy. Not bad mind you, no hangover or anything like that but I wasn't hurting that night for sure.
And boy was it nice to walk out and to our room at BWI. So worth the move over from CR