The only resort with adjoining studios is the Poly. It is a request, never a guarantee, although I have never heard of someone making the request there not getting it.
Add the request via Member Services.
All other studios in DVC either lock-off with a 1BR, or are dedicated and do not connect to any other room.
VB does have a limited number of connecting Inn rooms.
Other resorts either have adjoining studios or ones that are close by or across the hall from each other.
Requests for either adjoining or connecting is just a request and not guaranteed. At PVB though all but 2 studios connect to another studio and that request is one of the easier to get. I don't think I've heard a report yet that people haven't gotten it filled when staying there.
OKW has adjoining studios, but they are one on top of the other (not next to each other). You must have at least one adult, aged 18 or older, in a studio. You will never get a guarantee that they will connect, even at the Polynesian.