If you have a choice of Cypress Palms and Star Island, then choose Cypress Palms.
If Star Island has transportation, I think you would have to pay for it as you're several miles away from the Parks.
I think with the kids, you should go with a 2 bedroom as you have more room.
However, you could probably make do with the 1 Bedroom at Bonnet Creek as the Master bedroom should have a King Size bed. And the sofa bed isn't that bad.
If Sheraton Vistana pops up and no Bonnet Creek (I agree with Brian), I would jump on that. It's a nice resort.
And exchange availability can change drastically over time so I wouldn't wait too long for exchanging into August.