WOW, this could be the longest thread ever, this is a huge question. Planning a Disney trip is mind blowing.
We went last May and had a blast, we had a 5 yo boy and 3 yo girl when we went.
My sister is the 25 Disney trip veteran, we took some advice and skipped some other. We opted to mostly go and figure it out ourselves, and I think we did great.
The way we did it was shopped Disney on line constantly looking for discounts which usually come out just after Christmas, we ended up finding a 40% of package to their luxury resorts, we opted NOT to do any meal plan and I am happy we did not. In summary, the 4 of us stayed at the Grand Floridian last May for $3,300 that was Sunday through Saturday and included 5 days park hopper passes, no waterparks, kids too small, flight for the 4 of us was $1,050. I added up every receipt for food that we had and it totaled $750, we ate what we wanted and when we wanted, so round numbers $5,000 and we had a perfect room walking distance to Magic Kingdom with probably the best view of the fireworks there is, every night the kids sat on the balcony and watched them and the magic light parade.
We are going to go again this year and do the same thing, I like being flexible. My sister books virtually every meal 6 months in advance, the only thing we booked in advance where 2 character meals in Magic Kingdom.
The next time we book we are going to book in advance the 2 character meals but also book a princess lunch for our daughter. We found it IMPOSSIBLE to book a princess meal while were there, however, we were able to book a meal for just about anything else we wanted.
If you stay in the park one park opens an hour early every morning. What we did was get to the park on that day about a half hour before it opened, the line was still daunting but when the park opened after a few minutes it was easy to get where you wanted. So one morning we rode Space Mountain non-stop for an hour then we went over to Splash mountain and rode that non-stop then to the Thunder Mountain railroad. Then by like 10 AM it was starting to get packed so we would always do the fast pass ticket and basically go fast pass to fast pass, the lines go so that it was 15 to 20 minutes for every ride, even with fast pass, but that really wasn't terrible. We did the same thing at Epcot and the other parks.
Everyon'e experience at Disney I think is different. We really liked to be flexible so we didn't have to be anywhere at anytime and I think it worked great. Having little kids I don't think it is worth buying the meal plan, others may disagree. We loved the Grand Floridian and are staying there again with the park view, we checked out all the hotels and liked this one the best but others are really nice too.
The best thing my wife did was rent a double stroller for $100 for the week. They drop it off at the hotel then pick it up, full insurance lost or stolen. That made a huge difference, easier traveling, gave the kids a break and let us stash food and water for them.
Our big mistake was packing a big bag with food and snacks, could have cut that down to a couple packages of granola bars and raisins and stuff, food was expensive but it really wasn't killer. We bought those cups day one that you can refill so we had tea every morning, water for the kids all day and at night.
I was a disbeliever before but I found Disney really fun. That rat knows how to reach in your wallet for sure though.