Just a few things I noted as reading thru this thread:
I'm a little lost on the CCV resale - you'll have to be in a 2BR in just a couple of years to fit your family. CCV is a hard 4 count plus 1 under 3 in studios and 1BR's. I'd not even consider it if looking at value unless you were looking only for points to stay other locations and long term use there after the kids head out.
I think you can shake that thought.
DVC just isn't into deep discounts unless it's on very large amounts of points and they're wishing to bump up their sales numbers. 50 points and less is almost always at no discounts. Poly opening won't have an affect. In terms of selling DVC is in it for the long term. They also will sell multiple resorts at one time and actually can pretty much sell whatever they want to with a few choice marketing phrases. ie - if you're not willing pay $217 or whatever RIV might be at that time then cross that idea off.
FWIW - I love WL (1st contract was VWL (aka BRV) but also love BLT. There's a few of us that way. Although to be honest there isn't a DVC I dislike. lol Pluses, and minuses, to all of them.
June UY is what you want for a couple of reasons. Your planned trip times all fall before it's banking deadline in case of cancellation where you could still bank and 2) - your major trip will be in the summer so the most points to potentially have in holding etc and need the most time to rebook with. The best UY's are ones that give you a bit of "free" insurance in the way of more time to use the points if you have to cancel however any and all will work. Given the choice I would pick the best UY possible though for that protection.
Regarding resorts, this may not help much but thoughts are that I don't see summer availability changing a ton unless DVC does some really drastic changes with the
point charts for that time. (unlikely) Summer generally has good availability for 1BR's and 2BR's and even some studios so where you own is not likely to be where you have to stay. Your Nov/Dec is the more likely to be staying where you own but being those will just be a couple of nights generally then waitlists etc are easier to fill. Since you like SSR and would be fine staying there I'd consider that a good option. I also really think BLT could be a good one. I would not recommend CCV because of the 4 person limit for studios and 1BR's.
For the Poly tower I am expecting the point charts to be at the top so pretty similar to what you see for VGF charts.