We went with a 2 year old.
Magic Kingdom
We adored here; it is where the magic is - and this is what DLP is based on. But here is bigger. I'd imagine your two would love the Buzz Light year ride - and the eldest may get on the roller coaster. There is a children's coaster too. Not to be missed IMO
MGM
We really loved here. DD adored the Beauty and the Beast show. DH and my brother loved the Indiana Jones Show. All the adults enjoyed the Aerosmith coaster - very fast My mum and sister love Tower of Terror here. Not quite so busy here too.
Animal Kingdom
We were somewhat disappointed with here ,especially the safari. It was prety much a glorified zoo ont he whole, and the rides are very tame. Although I think they are having a new one here this year? However, the Lion King show is excellent and worth a viewing.
Epcot
Fascinating to walk round the different worlds, although apparantly England is just like Bath or Chester There other half is good too. I can image your two would enjoy the Honey I Shrunk the Audience 4D show - watch out for the mice and, your eldest may be able to go ont he car testing ride. The fireworks are good here we found.
Sea World
Shamu show at night is excellent (the rock show). Sit in the soak zone!!! Oh, and the Sea Lion show is really good too - don't miss it. Feed the dolphins and the Stingray. We spent ages witht he dolphins. The coaster here is great too - fast
Universal and Islands of Adventure
These ave more of the bigger/adult rides. The Mummy Returns is scary (but fab)! The Dr Seuss land is good fun for youngsters - take swimmers and a towel. There are two or three children's roller coasters here too. TBH there is plenty for them to do here, but maybe not enough to hod their interests for the whole fortnight.
Oh, and don't forget the Disney tickets include the two water parks - Blizzard Beach and Thyphoon Lagoon Both are great, but get there early, as the seats/loungers with shade go fast. Send one person off ahead of the others to grab some
It is all magical and great food. DD went around with the biggest smile and wide eyes for the whole fortnight. We didn't actually have a day off at all. The calmest day was the Space Centre, but even that was busy! It just seemed a waste to stay int he area and not be in a park - and DD just didn't want to leave!