I'm not sure how things work if you PAY to stay at a Villa, but if you stay using points as a DVC member (or renting from a DVC member) you pay extra points for a view.
So you are unlikely to get an 'upgrade'
The Boardwalk view is the MOST popular view of them all and it almost always sells out...and I means sells out in that people pay extra points to stay there with that view which they specifically book.
The 'problem' with this popular view though is that it can be noisy with the drunks stumbling out of the nightclubs at 1 and 2am.
As for where to stay. We have stayed at Boardwalk, Beach Club, AK Villas, Bay Lake Tower and OKW all in Studios.
I was unimpressed with Boardwalk because there is very little choice in terms of Counter service and the table service is either 2 credits or poor value 1 credit (Beaches and Cream.)
If you are into nightclubs though it might suit you.
As for Stormalong bay...I was underwhelmed but this is possibly because of all the hype it gets. BUT...it is the best of all the resort pools in size. And as a resort it is much more children friendly than Boardwalk and it actually CLOSER to Epcot than Boardwalk.
If you want this Epcot location I would suggest Beach Club over Boardwalk especially given the ages of your children.
If you are willing to look beyond the Epcot location then
The advantage of an OKW 2 bedroom villa is that the studio component is 2 queen beds and has the MOST room of them all. The resort has multiple pools with adult and children ones, but you aren't walking distance to any facilities beyond those onsite.
BLT was my favourite as you can WALK to the Magic Kingdom and the pool is lovely. It is also quick access to the monorail line.
You can get Bay lake or Magic Kingdom views but again you determine your view by the points you pay.
I don't know what happens when you pay cash though (other than that is costs more)