Hi! Here's my opinion, which is one of many you'll probably get

. I think it depends on what the kids like and probably whether they're boys or girls. Also, I wouldn't discount EPCOT yet!
At AK, things they may be interested in would be:
Wilderness Explorers badges
animal trails
safari
3 shows (FOTLK, Nemo, Birds of Wonder)*however it can be hard fitting all 3 shows in to a day, along with lunch and FP's, and as you mentioned AK closes at 5)*
It's Tough To Be A Bug unless it will scare them
character meets
Triceratop Spin
playing in Boneyard
**you also have Everest, Dinosaur, and Kali River Rapids IF they are tall enough (I'm not sure of height requirements off-hand) and not scared!**
Certainly enough there to fill a day. Now, HS is MY favorite park, but for kids the ages of yours, and since you're only doing 2 parks-I don't know

. Your choices, in my opinion, would be:
Shows-BATB, Indiana Jones, LMA, Frozen sing-a-long (again, fitting all in is somewhat difficult in one day)
character meets
VOTLM attraction
Disney Jr.
TSMM
Great Movie Ride
Muppets 3D
TOT?? *4 and 5 year old may be tall enough, but are they BRAVE enough lol*
I assume RnRC is out for the kids. You have the Animation Academy which I LOVE, but again giving my opinion, with the exception of maybe the 5 year old they are probably too young for this. So, not quite as much here as at AK.
Now, EPCOT! I think, depending on their likes, you may find more options for them here

In FW alone you have:
both innovations buildings
Spaceship Earth
Nemo
Turtletalk with Crush
exploring the aquarium
Figment plus interactive stuff after it
TT - if the older 2 meet height requirement - and all the interactive stuff after it
Soarin (height req.)
Living with the Land
The movie in The Land building, upstairs, with Simba. I can never remember what its called!!!
character meets
In WS:
the KidCot coloring stations in every country, even if they only color for a few minutes it can keep them happy and they may let the adults stroll that country a little more slowly than if they didn't have that coloring break

Boat ride in Mexico
character meets - quite a few if you look them up
some of the entertainment. My boys always enjoyed the acrobats in China
Agent P missions (at least the older 2)
While all the parks have good/fun restaurants to eat in, and I don't know if you're planning to do a TS each day, EPCOT has Askershus and Garden Grill, both character meals, and Coral Reef. CR isn't a character meal and while some people strongly dislike it, others love it. It has a huge fish tank in the middle and if you can manage to get a seat with a view of that, kids can enjoy eating there, too. Am I trying to push EPCOT? LOL no; as I said HS is my favorite park; but I do think some people overlook how much EPCOT actually DOES have for children. My boys have loved EPCOT since they were toddlers. Whatever you decide enjoy your trip!

But come back and post which park you decide to go to; after all this typing I deserve to know!
