Yes, they are part of the Disney Collection. I believe that the only resorts that do not participate are ones with DVC resorts appended (WL, YC/BC, BW).
The All-Star and Pop-Century resorts are also not options. The ability to stay at the other WDW resorts is to provide variety and a "change of pace". It is much more expensive point wise to stay at these resorts than it is to stay at a DVC resort so it's not something you'd want to plan on doing on a regular basis.
It cost more points to stay at WDW resort room - than a 2-bedroom - go with the 2-bedroom or better yet - get a studio about the same room size alot less points.
now after I said that we are using points to stay at the Contemporary Tower - because that is mother's favorite place to stay - and she is turning 81 - so I don't know how much longer she can go. but just one night - when the MK is having their fireworks - the other time we are in a studio at VWL.
the only time we used points for the entire trip was the Polyn (we were upgrade to a Lagoon view) - beautiful - but we both missed the 1-bedroom at OKW - it was enough points for a 2-bedroom at OKW - but all the DVC resorts were full when I try to make the reservation.