How old are the kids? We went 18 months ago with our 4 kids, then aged 3,5,7,9 and they each enjoyed different things. We took them out of school and lines were still longer than I thought they would be. We stayed on Disney property and didn't go to Universal Studios. Even though we were there for a week, I'm glad we didn't try to anything else. If you search for threads on here, you'll find some good info as a few people go regularly. If you want to maximize your time at Disney, buy the book "The Unofficial Guide to Disney World". It reviews every park restaurant, let's you know what the best deals are, helps you with ride strategy so you minimize your time in line, etc.
Also, while you are there, make sure you download a line wait time app for your phone so you can easily tell how long waits are.