S.,
I am all for WDW in Florida. I have been there twice and Disneyland twice. Florida gives you way more for your money and everything is right there in the Disney Park. Example...
Magic Kingdom, Animal Kingdom, MGM Studios, 2 waterparks and Epcot come in a package with free transportation between them all. It takes a week to see it all. (Dining packages are a good deal if you stay onsite.)
With Disneyland, you get in Magic Kingdom and California adventures. Want to see animals - pay again and go to Sea World or a zoo. Want to see movie stuff - pay again to go to Univeral Studios. I can't even think of a good comparison to Epcot. And you will most likely have to rent a car. Definately no jumping from one place to the other on the same day. (Dining package here isn't really worth the trouble either.)
We used Teresa Cory with Small World Vacations (I think she does Disneyland and Disneyworld both) and she was great. Found discounts a few hundred dollars lower than I could after more than 6 months of research. www.smallworldvacations.com
You may want to consider staying onsite. We went two years ago and got a value resort room for $62 a night. It's nothing fancy, but it is clean and they give you free transportation to and from the airport and to and from the parks. And we only slept in the room, so we didn't need a lot of perks anyway. When you think of how much it is to rent a car and pay parking every day, it makes sense.
We also did the dining package, only available if you stay onsite. It is $38 per adult and $10 per kid per day. You get credit for a sit down restaurant meal, a fast food meal and a snack every day. (Both meals come with drink and dessert and include tip and tax.) You can use them however you want and split any meal except the "all you can eat" style restaurant. It was more than enough food for our family. If we had gone offsite to eat at McDonalds, we would have paid the same over a week and walking into the WDW restaurants you pay WAY more than if you pay in advance with the dining package.
There are some great websites out there put together by moms who are Disney nuts - go multiple times a year. These may help no matter where you decide to go.
www.allearsnet.com
www.mousesavers.net
Recognize that if you go when school is out, the prices are at their highest and the crowds are awful. Trip #4 for me was the first with kids. We went the first week of February, got fantastic deals and rarely waited in line for anything. (15 min tops for the most popular things.) When I went over the summer it was HOT and HUMID and you waited in line 30-60 minutes per attraction. I have never went over spring break, probably good weather, but crowded none the less. I am not a "pull your kids out of school" kind of a person, but for this I would make an exception because I have seen the crowds both ways and I would NEVER take kids during the crowded season.
Hope you have a great vacation,
S.