I initially thought the Polynesian, but then thought a moment more and decided with children those ages, especially the infant, I'd choose the BWV.
Reasons? Lots!
The washer and dryer right in your room is a HUGE plus! Having a seperate living room where the kids can sleep, and bedroom will be great for a number of reasons... when you need to nurse or feed the baby at night, you won't wake everyone up, when you put the kids down to bed for the night you and your husband can watch tv in your room, or better yet you can take a long relaxing soak in the jacuzzi tub.
Oh, did I mention the kitchen? The kids wake up in the morning hungry, and you and your husband can tag team getting yourselves ready and feeding the kids right there on the spot. In the evening you and your husband can enjoy a bottle of wine--the kitchens come equipped with a corkscrew and wine glasses. The full size fridge is great for snacks, holding formula or breastmilk if you need to pump, and there's also a microwave. Plus there's plenty of freezer space to hold ice cream!
The kids are done eating but you're not ready to go? No problem! Slip a DVD into the DVD player and let them watch a Disney movie!
If the weather is bad you'll have plenty of room to spread out and not be on top of each other. If someone is sick, same thing.
And Community hall is a great place for the older two to spend some time while the baby naps.
The pool at the BWV is perfect for that age group, IMHO SAB is too large to keep track of kids in. And an added bonus, the kids are allowed to wear a life jacket and go down the slide at the BW pool!
OK, I think I've made my point
We stayed there last year with my sister, BIL and there three kids 7, 4, and 14 months. It was absolutely a perfect location. And BTW, not all kids are enamoured with the MK. My neices and nephews all prefer other parks, it's a toss-up between Epcot and the AK, depending on which child you ask and which way the wind blows
Anne