We save change, charge everything that we possibly can to our disney visa and then pay it off in full each month, for dh and my birthdays and anniversary we put in what we would have spent on each other in the account unless there is something that one of us really needs.
We also stay value resort, pack snacks, have never done the dining plan or a character meal, we also do not go overboard on souvenirs and have brought things along from home to surprise the kids.
What works for us doesn't work for others.
Look for deals and take advantage of them
March 2009 - buy 4 got 3 free deal with $300 gift card - went the week of youngest DS birthday so he was free. used the gift card to buy meals in the park. most expensive trip thus far because we didn't know if any better
April 2010 - had enough disney reward points to pay for our campsite. Bought tickets from
Undercover Tourist then ugraded to APs. Saved about $125 on the 4 tickets and reward points covered the upgrade cost. Also (thanks to the Creative Disign board) made 9 days worth of matching tshirts - we will be using the shirts for our 3rd trip this april
Oct 2010 - room covered by reward points, no cost for park tickets with APs, reward points covered our
MNSSHP tickets, 4 roundtrip airline tickets with a flight credit $376, rental car for 10 days $205, plus food. (both DH and I took advantage of the 200 points for getting another visa card an easy 400

)
April 2011 - AP rate on room and over half to be paid for by reward points, no cost for tickets still using APs, driving instead of flying (saving about $750 over flying and rental car)