We go to Disney quite a bit. I'd highly recommend mousesavers.com and allearsnet.com in helping to plan the trip.
When are you thinking about going?
I'd recommend staying on-property for several reasons. The first is that you can take advantage of the extra magic hours. The second is that you can get room, ticket, and dining packages. I read somewhere that Disney extended their free dining offer through September 2011, but I can't remember where I read that, but it'd be worth asking if you call to make reservations.
Buy your own water and carry it with you. We usually go to walmart/sams club/target/costco and buy a case of water and bring it with us. You can bring it into the parks, no problems. Also, we bring in our own snacks. They don't want you bringing in a cooler, but throw it in a backpack, and you're good!
Buy breakfast items and eat most of your breakfasts in the room. We've found that breakfast is probably one of the most expensive meals at Disney for what you get. We've been known to bring cereal, breakfast bars, and poptarts. Anything that's "easy".
Anyone can order a child's meal (at least from counter service restaurants). I've had my fair share of kid's meals to cut down on the amount of food. Also, if the kid's meal comes in special packaging (some places put them in plastic lunch boxes), ask them to do it without the packaging, it'll be about $1 cheaper.
For family pictures, someone suggested buying the photopass before you go. Even better, give the photopass photographer your camera. They'll take a couple with their camera, but they also will take pics with yours. Some of theirs will be a little more fun than what ends up on your camera, but that has to do with their ability to add special touches. Honestly, the last time we bought the photopass pics was in 2008. If you do decide to pre-buy, make sure to get as many pictures done as possible.
There's soooo much to do at Disney without going into the parks. The hotels, in and of themselves, are amazing to visit. Downtown Disney is a lot of fun to visit (and I love lunch at Earl of Sandwich). Then, of course, there are the pools at the hotel.
Sometimes AAA has deals on tickets/hotels. If you do a package, it can't be combined; but if not, definitely ask.
Now you have me wanting to go back. <sigh>
