I think we are fairly typical of the families that you are refering to. A family of three (smaller than most), middle income, etc. Yet last year we did 5 disney trips, with a total of 5 weeks on-site. Loved it, and wouldn't mind repeating it.
So how do we manage it ?
* We use annual passes. That greatly reduces our admission cost versus other media.
* We are DVC members. This takes care of at least half of our accomodations. We also enjoy other disney resorts, and have taken advantage of whatever discounts that are available to stretch our stays.
* We owe on nothing except our home, and pay our c/c in full each month.
* We drive down (company minivan.) Travel cost = $0
* We have been to disney enough to know what restaurants we like, and which we don't, and the ones that are the best values. ALot of guidebooks mention that a family of four will often spend $200 a day for food. Even when staying non-dvc we have never come close to that. When staying in a dvc resort we spend even less.
* We're lucky that none of us would be considered very materialistic. We like nice things, bu have no desire to buy everything we see. The souveniers from our last trip were some shirts and other things from the outlet store offsite in the premier mall, and some antenna toppers. I want something to remind me of the trips, so that I can experience the memories again.
* If there is something we want - but don't need at that moment - we wait for it to be reduced to a price we are willing to pay, or have saved the money to pay for it. I've found that if you are willing to wait for a purchase that getting something for half off is usually just a good starting point, but you can often get it for less.
* We've made vacations a priority.
I hope this helps. Good Luck !