1st, you are on monorail line and you can zip back to hotel for naps and don't have to worry about buses (you can also take a cute little boat). I would take Poly over AKL with younger kids just fo that reason.
Poly has a nice sandy "beach" area for kids to play. Zero entrance pool area--great for little ones and rock slide perfect for a 6 yr old. Nice tiki bar right by pool. Free life jackets. PAddleboat, etc. rental. AKL and Poly pool aer a too-up, but I like Poly's a bit more. Also, I like Poly's grounds. You can go over to AKL lodge and walk around, go for kids activities, or evening for firepit, and walk on walkways to view savannahs.
At Poly--Ohana's has character meal for breakfast and fun dinner. Kona CAfe is supposed to be very good.
Also, easy monrail ride to Contemorary, in case you are doing Chef Mickey's. Rooms used to have 2 DBLs or Queens with daybed.