Do you have 3 full days, i.e. a 3-day park hopper pass of some sort? I don't know how old your kids are, but first on your list, IMHO, is Magic Kingdom. If your kids are young, too, I'd probably do MK for 2 days, taking a break in the afternoon to swim at the Poly pool and relax, and nap if at all possible. You'll have much more fun if you don't try to do all of Magic Kingdom in a day and kill yourselves in the process. After MK, I'd pick AK personally, or MGM. Epcot is really good for older kids and adults, but when mine were younger, there was not as much there that interested them.
You might want to buy the Unofficial Guide to WDW, if you haven't already. It will give you a lot of good advice on the best times to see what attractions, etc. Be sure and take advantage of the Early Magic Hour for MK, if it happens while you are there.
Last bit of advice: recognize that you will not be able to see all, even if you were staying for two weeks. Make notes of what you are missing and want to see next time, and when you get home and are depressed that your trip is over, start planning the next one!

iluvtink