If I were taking three kids to WDW I would ask them how they want to spend their time, not a bunch of strangers on a forum.
What makes you think the OP hasn't also talked to his/her family? The forums are here to get ideas from other sources too.
We have 6 full days plus half day on our departure day. We're staying at VGF in mid-May with three kids ages 9, 7, and almost 4. Our youngest usually naps but sometimes skips and may outgrow by then so that's flexible with our touring. How are mid-May crowds these days? We would like a little pool time and DTD time. We are hoping to go to Typhoon Lagoon...does that need a full day? How would you divide your days/time between the parks? Thanks for any suggestions!
Mid-may days are moderate. Not the busiest times, not the slowest times. I just went in May and found the crowds to be okay.
I would do 2.5, 2, 1, 1.
2.5 days at the MK
2 days at EC
1 day at HS
1 day at AK
I would also work some other stuff into the 2.5 MK days, so while this may seem like a lot of days, I look at it more like 3 shorter days, with half of each day doing something elsewhere.
TL - no, I would not give this a whole day. More likely, I would plan a morning / afternoon at TL, with plans to go to the MK that night for a bit.
You could also pull a half-day from Epcot, but only you know how much time you want to spend at each park! Or if you feel you want to only do a day at EC, this would make for a more relaxed trip with more resort time, putting TL on one day and EC on the other, then not having to split an MK day.
With only 6.5 days, I would probly squeeze DTD out of such a visit. Or just do it for a couple hours in an evening. Like if say, you were to want to visit HS, then walk to the Boardwalk and catch a bus to DTD, by the time you're leaving HS, you'll probly feel like it's time to go back to the hotel and swim - that's why you're leaving the park after all. Not to go walk around somewhere else.