I'd certainly skip Sea World. It will be far less expensive to stay at WDW forone thing - and you'll still miss much of it.
I'd probably pick one day in each park: MK, Epcot - then either HS or AK.
I think Missing Epcot is a big mistake. The kids in our family love it. The Nemo ride, Figment ride, Maelstrom, Spacehsip Earth, Mexico, Canada Movie, World Showcase, Test Track, Living with the Land, and Soarin' are all big hits!
not to mention Epcot has mcuh of the best dining in WDW! Especially many of the best QS places.