As far back as I can remember into childhood, Disney World was The place to get to. The first time I ever visited I was 7 years old, and it is something that stayed with me to this day... it really is a magical experience and everything I had hoped it would be.
Someone once described Las Vegas to me as 'Disney World for adults'. And that is very true in that is in a place as wonderful and as far away from real life as you could possibly hope it to be. The only problem I have with the comparison is that Disney World, in many surprising ways, is also Disney World for adults. This is a theme park that changes and updates and grows and improves constantly... so even if you took your family 5 years ago there are almost certainly more and newer things to see now.
If you went as a child and are thinking of sharing the experience with your own family, you won't be disappointed. Even as an adult this is a place that is so incredible that it can really be enjoyed by everyone.
It's also rather vast though, and depending on the length of your stay and how much time you want to spend at the Disney theme parks, it can take a fair amount of planning (both financially and for scheduling). It's worth it though, and if you check out their official website it is very useful and well laid out. A great tool in planning the trip. If you, like me, are returning to a modern Disney with the fond childhood memories, 'Oh! Space Mountain was wicked! I wonder if they still have the Haunted Mansion?' The answer is yes... many of the rides and attractions we all experienced with such nostalgic wonder are still there, though some have been improved upon, along with a whole host of new generation rides, sure to be appreciated by the younger crowd.
I can't really say enough about what all the Disney theme parks have to offer. Big, thriller rides for older kids and adults, small child rides well done and beautifully themed. Shows, restaurants, luxury accommodation, studios... there are very few interests it doesn't cater to in some way or another. It's not a cheap experience, but at least in this you do get what you pay for.
As with almost any theme park, the earlier you get there the better. Walt Disney World is notorious for its incredible long lines, and remembers you will be standing in them in Florida. Go in the off season if at all possible, but if not prepare yourself for the bustle and the lines and enjoy what theme parks are all about!
This really isn't something you should attempt on a budget (and as you know I rarely give advice on non-budget trips) but it has so much to offer, it would be a shame to lessen it by constant financial worry.