I can't be any help on the Swan and Dolphin b/c I've never stayed. I did however, just plan a trip for 20 people (we leave next Saturday!!!) We were originally staying at POP! so that everyones budget was taken care of. Then we came across a deal with DH's aunts timeshare (she is coming too). So we went with that we ended up getting 2-2BR units and 2-Studio units (that we rented from a
DVC member) at BCV for about $4K total. In the end it cost a little more than POP, but only about $300, and when you spread it out over that many people it isn't much at all. Have you looked into renting points from BWV and maybe getting 2BR units and splitting the cost?
At one point we did have one of our 2BR's at SSR b/c that was available, but I was able to switch it when BCV came available. It wasn't a big deal to us to be in different places. At point my sister and her family and my mom were going to stay back at POP! or one of the All Stars before I got them points at a good price.
Another thing I have learned through this experience, No one will ever agree! There is always at least one person complaining. I made the majority of my group do a compromise. Most have never been there, so they pretty much left the planning up to me! I have done everything for this trip from buying the tickets, making the resort reservations, making ADR's, making our touring plan (we are going on our separate ways for the most part in the parks), deciding when we are leaving, what cars we are taking, and who is going in which vehicle.
The largest ADR I have is for 16 at Cape May for breakfast. It was difficult, but I didn't start trying to book until the end of November (due to some dragging their feet on if they were getting the dining plan or not).
If you have any other questions about planning for a large group, let me know. I am by no means a "Disney expert", but I can try!