The most important thing to remember is don't get overwhelmed. There's so much to do so decide if you want to do mostly rides, character meet and greets, mostly walk around and take in the sites and eat, all of which are great options. The problem might be in the ages and what they like, i'll list the rides and attractions for MK and break them into kid friendly and such so you can have an idea on what to definitely do or what to stay away from things may get too scary. Also fast passes are a must for certain rights to i'll put an "*" on ones you will need to fast pass if you really want to ride them.
Family Friendly: Jungle Cruise, Enchanted Tiki Room, Hall of Presidents, Peter Pan* (must do and a must fast pass), Enchanted Tales with Belle, Winnie The Poo, Little Mermaid, Small World, Mickey's Philharmagic, Tomorrowland Speedway, Buzz Lightyear, Carousel of Progress, Tomorrowland Transit Authority
In between: Pirates if the Caribbean (slight drop but nothing serious, highly recommended), Haunted Mansion (a little spooky but not scary my personal favorite ride), Seven Dwarfs Minecart * (a very small roller coaster), The Barnstormer (another small roller coaster)
Thrill Rides: Splash Mountain* (log flume ride with a 50 foot drop at the end), Thunder Mountain* (Medium roller coaster), Space Mountain* (roller coaster in the dark)
As for AK there isn't much to do in way of rides and everything is very spaced out so there will be a lot of walking in between attractions, the park will probably only take you 3-4 hours to complete so don't expect a full day like in MK. The Safari and DINOSAUR are things everyone can do but Expedition Everest is an intense roller coaster (by disney standards). Kali River Rapids is something that should be ok there's a slight drop and note that you will get soaked. Other than that there's a bunch of shows and movies like a Bug's Life and the Lion King that you can do along with a nature trail.
I hope this was helpful anything else you have questions with I will be more than happy to answer them.