chknmama and Arkiegirlwelcome to the DIS!
I give this advice to everyone who asks me about what they should do at WDW...RELAX!! Take your time, no matter how long or short your vacation, you can't do or see everything. Why try to rush your way through, wou'll end up tired and miserable.
Get yourself a guide book to WDW. There are quite a few, my 2 favorites are the Passporter and Birmbaum's Unofficial Guide. Here are some of the things I would see at WDW if I had kids 4 & 6.
Get close to the Castle
take in at least 1 parade
see the fireworks
ride the monorail ask if you can ride up front, sometimes they will let you but now it seems only if you are getting on at one of the monorail resorts.
try to get a Meal where you can see and meet characters, check out this link:
http://www.wdwinfo.com/Just_for_kids/character_dining.cfm
Do some rides and let the kids be kids. Read the books and figure out which ones you'd like to do.
Epcot can be a great place for kids. Especially if you let them play in the various fountains found around the park. My kids spent at least 2 hrs in these and had a blast. It was also great for mom and dad to take a break.
There are a ton more things I could mention but I tend to ramble and you'll soon learn you can't get all the info all from one spot.
Have fun...and relax!