I think you're in the same boat as us... thinking about it for years... we do the math every year or two, and until recently it's always been better to rent on the hotel side. But once you outgrow the 5-person limit,
DVC starts to look more appealing... So we just bought in! Waiting for ROFR now.
UY... If you would go Aug-Dec, then an Aug UY is ideal. June UY is good if you like the summer months. It comes down to when else you might go. After Aug-Dec, are you more likely to go in Jan-Mar or Jun-July? That will tell you if Aug UY or June UY is better for you. You should look at a few consecutive months that you don't see ever going, and pick right after that for your UY. And it's not that big of a deal really, it only affects your ability to bank after cancelling a stay late in your UY.
And don't overbuy. We bought in w enough to go every 2-3 years, so we aren't oversaturating ourselves w the same place every year. You can always do extra trips by paying cash for hotel rooms... or top off your points later, or even pick another home resort to buy into! You mentioned AKL and BCV both... so leave yourself the option to buy into some of the other one later, whichever you don't buy now.
As for DH, I would not plan to transfer your points out to another timeshare. That'd be a big waste of expensive points on some place cheaper. One situation we both agree we won't be in is sitting on points we can't / don't want to use. There will always be a friend / family to rent them to if we don't go, or just sell / transfer them for a year on the open market and make a little money back on the investment.