MK: Mickey's Philharmagic (I have a 11 yr old son and 9yr old daughter btw), all the Mountains, Pirates, Peter Pan, Haunted Mansion, Buzz Lightyear, Spectro, Share a Dream Come True Parade, Wishes.
Don't do's at MK: Dumbo, I mean its a famous Disney ride but don't waste too much time in line (which builds first thing and never stops). It lasts about a minute and half and given the age of your kids, might not be worth the hassle. But then again, its such a Disney classic! We don't usually ride it because we hate lines. Also Country Bear Jamboree. We like it fine but only do it when we have done everything else. Aladdin's Magic Carpets, its just like Dumbo but you are on a carpet. Tiki Room, we have seen the better version at
Disneyland, the WDW one is kinda lame. But if you need a place to cool down and rest it comes in handy! Alot of people will tell you skip Stitch, but if you have Stitch fans you might want to check it out, just don't stand in a long line!
MGM: Must do's: Rock N Rollercoaster, Tower of Terror, Star Tours, Great Movie Ride. The Stunt shows get mixed reviews, we enjoyed the Indiana Jones one, your 10 yr old boy would probably love it, my 11 yr old did. My 11 yr old also loved the Lights, Motor, Action one too. Fantasmic! for sure. My whole family loves this show and can't miss it. Voyage of the Little Mermaid and Beauty and Beast are musts for your daughter. Although my son enjoys those too, especially Voyage of the Little Mermaid.
Don't do's for MGM: Muppets 3D. My kids aren't familiar with the Muppets and hated that show. They also thought the backlot tour was boring except when they sprayed about 10,000 gallons of water on the ride vehicle. We rode it once and probably won't again. The Stars and Motorcars Parade is boring to my son, my daughter likes it okay. Its the cheesiest Disney parade I have seen.
Epcot: The whole Future World section. My kids love everything, especially Test Track, Mission Space, Soarin and the Universe of Energy, they also enjoyed the Living with the Land boat ride and the Circle of Life movie. Both of those can be done while you wait for your Soarin fastpass to come up since they are located in the same building. In World Showcase, The Impressions de France movie. My kids enjoy this, its very relaxing, you can sit down and the screen is circular which is cool. American Adventure is very intersting but my son always falls asleep! Daughter loves it though. They also like Maelstrom in Norway and the Mexico boat ride (that one seldom has a line). Illuminations is a must too.
Don't do's: World Showcase is something my kids get bored in except for the above things I mentioned. Honey I Shrunk the Audience. Its a bit dated and takes awhile given the length of the preshow.
AK: My kids love everything at this park. Obviously Dinosaur and Safari are musts but they also love Primevil Whirl. Festival of the Lion King is great as is the Jammin Jungle Parade. My daughter loves the Pocahantas show, its not the best but she thinks it is!
I guess Triceratop Spin is something they skip, its Dumbo on a Dino. I also don't let them play all the games back in Dinoland, they are so expensive. If you are staying onsite your resort will have an arcade, way better useage of spare change!
Wow, that was long. But our kids are close in age so I just though I'd give you our run down's! Have a great trip!
Edited to add, I see you are staying at POR, my kids loved that resort. The pool is awesome with a great slide. We rented a surrey bike one day and they had a ball. Great choice on your resort!