Nust do's for this age group are:
DL:
Get a first time button at city hall
Get a GIANT cookie at the main street bakery
Bring an autograph book
Toon Town charactor meet and greet and home exploration
Buzz lightyear astroblasters
Winney the pooh (charactor meet and greet outside the ride too)
All of fantasyland
Its a small world
Tiki room
Tom Sawyer Island
Shooting range in frontierland
Big Thunder Ranch
POTC
Autopia
Tea Cups
Finding nemo submarine ride
Jungle Cruise
Parades!
Fitrworks--observation deck of the future house in tommorrowland is a great place to watch
If they are braver, all the thrill rides are great, as is the haunted mansion
DCA:
Playhouse Disney
Aladin
Toystory Midway Mania
Monsters Inc
All of Bugs land...although the movie can be scary for little ones
Turtle Talk with crush
Muppet vision 3D if they like the muppets
Pixar play parade
Again if they are more adventurous go for bigger thrills, soaring and grizzly river run are great and not too scary. If you have any other questions feel free to PM me, I'm going with my 3.5 year old again in 2.5 weeks
Ohh be sure to take a break during the day and a stroller wouldn't be a bad idea, even for the 5 year old! Above all enjoy yourself and don't forget to look for the hidden mickeys!