This
I think the only way to create a realistic budget is to mock plan the trip and price everything out (hotel, park tickets for both parks, food, use gasbuddy.com to estimate cost of gas, parking, food menus, etc). There are so many variables to the ways people travel. A family of 5 who drinks alcohol, wants a character meal, and room service each day will have a much different food budget than a family who eats breakfast in the room and shares counter service meals. A family staying in a 1 bedroom suite at the GCH will have a much different hotel budget than a family staying at Candy Cane Inn. None of these choices are wrong, just different. Budgets are very family-specific.
I make an Excel spreadsheet and list out all of the anticipated costs.
this is what I do. I even peek at menus. I then add 10% to my food budget for good measure- also for table service don't forget to calculate your tips of at least 20% into your budget. I always build my dream trip and then start to cut things out to get to a number I feel good about.
If you wanna see my crazy, the 8000 budget I mentioned above is broken down below and has a bit of a cushion..
$2800 hotel/ticket package for the anahiem hotel for 6 nights, 5 day 1park per day tix with genie + (yesssss I got a good deal)
$600 estimated for oogie boogie bash for 4 people
$1200-1400 Southwest round trip flights from Omaha to SNA (if you are a Sam's member you can get $500 SW gift card for $450)
$200 rental car
$200 BBB (please please come back)
$100 droid for the boy
$100 lightsabers in Tomorrowland
$320 world of color dessert party
$260 Blue Bayou Fantasmic lunch package
$250 goofys kitchen and tip
$300 princess breakfast for 2 and tip
$125 lamplight meal with tip
$200 kids souvenir money (us adults don't get a "set amount" hehehe)
breakfast for 7 days: $200 ($30 a day)
9 QS meals at $60per per meal: $540
snacks: $75 per day: $525
I probably estimate high on snacks and QS, but it's Disney. I also realize someone else looks at my budget and thinks it's nuts. Note my cheaper hotel, but that's because as you can see we like to do the special things In the park. We don't go often so when we go we tend to spend more.