I recommend you stay in only one hotel. The gap from the 11AM checkout to 3PM checkin is only 4 hours, but in practice it can be much more. It is easier to checkout when leaving for the parks in the morning, but you will not have a room for an afternoon rest. I had a room (VGC 1 bedroom) not available until almost 6PM

There are conflicting reports about the availability of bell services transferring bags between hotels, so you might be stuck dragging your bags across the street. This is not a big deal, but does conflict with the "concierge experience"
IF a special comes out sometime soon, our goal is to do all 8 nights at the GCH but we'll see what happens. We know that not having a room ready for us that day could be a possiblilty but we also arent planning on going to the parks in the morning so it would be ok to check out of PPH and go to the park (after leaving our luggage with the GCH and picking up a few drinks in the conceirge loung) then come back when our room is ready then head back out to the MHP, that is our plan for the 18th, keeping our fingers crossed we can avoid all that hassle and just get an awesome rate and do ALL nights at GCH
If you are able to get a king bed both your kids would sleep on the floor, so this seems like the worst possible room type. The best room would be 2 queens and a daybed, which is very rare at the GCH (39 out of 1000, and no view). 2 queens and a daybed is the standard configuration at PPH

Another option at GCH is a queen and bunkbed.