Phew, I finally read your PTR. Really enjoyed hearing about your family and, of course, your trip to MOA.
A Peeps store! I do love me some bunny peeps. Looks like you guys really enjoyed your visit to MOA and to D~'s house for the big birthday party. Those pin boards are a great idea, your kids obviously loved them too.
I just saw bubble gum peeps at the grocery store!
Not sure about this service but I have always setup a little surprise for the kids to announce an upcoming trip to Disney. We always get a "letter from Mickey in the mailbox". This letter usually comes on a Sunday morning and we know it is in there because there are Disney balloons tied to the mailbox. Well for our last trip my DH blew it and told my daughter at lunch one day (I think he wanted to be the one to tell her. She told him "but we always get a letter from Mickey") I am still mad at him for ruining the Disney magic

I usually include some cute little Disney themed items, a countdown to our trip, a note from the gang and one year I added the Disney luggage tags all filled out for each member of our family.
What a great idea!
As for when you should go to Disney, I'm not sure what your schedule is but, I like to make the most of the "extra" days on the weekends for travel, park time or just getting settled back home. If you can use both weekends it gives you "extra" time. DH and I were at Disney a few years ago right after Labor Day. We arrived the Sunday of Labor Day weekend. The parks were VERY light that week (even Monday) as most kids were headed back to school and the locals were back to work.
I didn't think about "travel days" and the extra days with going from weekend to weekend...
Maybe plan to drive and if you find super cheap airfare you can just fly. Would you be driving non-stop or are you planning on breaking up the trip? If you have to add in the cost of gas, meals and hotel for your travel days then the cost to drive might be comparable to flying.
One more thing (and anyone feel free to correct me if I am wrong on this): Disney considers a person who is 9 years old a child and a person who is 10 and adult. If you check in on the kids' 10th birthday they will be considered adults. If you check in the day before their birthday Disney considers them children for your entire stay. Park tickets
MNSSHP tickets and dining will all be cheaper for a kid vs. an adult.
Sorry for the super long post. I hope I can keep up with your PTR