Here's my recommendations:
I would say that you should spend 2 full days at the Magic Kingdom, 1 at Animal Kingdom and 1 at Hollywood Studios. I would reserve a full day for Epcot, but you could spend the Early morning there, head back to the hotel for a swim at the pool and a nap, and then return for dinner and the fireworks.
For 5 days, here's what I would recommend:
Day 1: Magic Kingdom
- You have reservations at Ohana, so it'll be easiest to arrive, maximizing your park time. Also, Magic kingdom is always a great first Disney park for the little kids.
Day 2: Animal Kingdom
-I know people said to put it in the middle, but it's a good park to do after a long day at MK
Day 3: Hollywood Studios
- You already have Fantasmic reserved, so I won't change that around
Day 4: Epcot
- I nice nap and swim in between the morning and late night would be nice after a long few days for your kids.
Day 5: Magic Kingdom
- It's always nice to finish a magical tip with the Magic kingdom!
No matter how you plan it, I know you'll have a wonderful time!