If I were you I would rethink the late nights unless your kids are used to them. My DD's are 6 and 3 and they are normally sleeping by 7:00, so a 9:00 start time for dinner would be asking for trouble with them.
At home we normally wake up by 5:30-6:00 for work, so sleeping in until 7:00 is a dream for us. So, we just got back from Disney, and were there in September during a "slower time" and left our condo between 8:00 and 8:15 (Windsor Hills).
Our first day was Epcot and we were there by 8:30 ish standing at the turnstyles. We were on the 2nd runthrough of Soarin'. By the time we got out, I believe the wait time was already 30 min or so and the time was only 9:15. Before 10:00 we did nemo and the seas pavillion and figment and that pavillion in addition to Soarin.
The lines start off small and just continue to grow and grow throughout the day, and with most nights at the parks having fireworks or nighttime entertainment, I didn't find the lines slowing down come evening.
Regardless, we went to MK the next day and planned to stay late for fireworks so arrived around 2:00 pm and the place was a zoo! We did get a lot done, but it was just so much stressful trying to move around the sea of people.
On our Hollywood studios day, we planned to arrive around 8:30 but ended up lost and by the time we got into the park it was about 9:02 and the rope had already dropped and we were at the back of the herd going to TSM. We knew we wouldn't make it to the ride in decent time, so stopped by animation courtyard where there were 6-7 characters the kids got to meet with ZERO line up. We made it to TSM I think around or just before 9:30 and the fast pass line had a 5-10 min wait, and our return time was 11:30. The main ride I believe had a 50 min wait already. I have heard though that the line ups and fast passes are even worse now though. Remember this was on a 1-2 day on the crowd calendar.
On our AK day, we got there about 5-10 min before they dropped the rope and we went to camp minnie/micky and the kids met - Minnie, Mickey, Donald, Chip and Dale, Goofy, Thumper, Miss Bunny, and Meeko, by 9:15! By 10:00 we had done Lilo and stitch meet and greet, bathroom break, Triceretops spin, and Dinosaur and were waiting in line for Expedition Everest!
Our last day at MK we got there in time to see the RD ceremony. We did meet and greet with stepmother and stepsisters (first family of the day!), Peter pan, winnie the pooh, and Snow White by 9:30. We then went to wait for the toon town opening. At 9:45 it opened and we were in the 2nd or 3rd group let back to meet the fairies. By the time we got out of meeting them it was just around 10:00 and the time was 75 minutes!!!!

The princess line was 15 min so we went to meet them, and when we came out it was around 10:15 and the line up for the princesses was 40 min as well!
Our strategy with our kids (who don't nap), was to get there as early as possible (except our fireworks night). And we took a rest day the day after our fireworks day. We did as much as we could and then left in the afternoon between 3-4 o'clockish, went back to resort for rest and swim time. Then relaxing evening and early bed!
Worked for us, when we spent that much money we wanted to see as much as possible, but it all depends on your priorities. BUt if you're up by 7 anyways, no reason you can't be there for RD... BUT I would rethink those late nights with such young kids!!!!