Linda, the Dolphin and Swan are on Disney property, but they are not "Disney" hotels. They are independently owned and they license the "Walt Disney World" name/logo. You'll notice the difference in their names vs. other resorts. An example:
Walt Disney World Dolphin (or Swan)
Disney's Polynesian Resort
Disney's Contemporary Resort
Disney's Port Orleans Resort
If you stay at the Dolphin or Swan you are in the middle of WDW. I don't know if you can add-on Ultimate Park Hopper passes or not. I was told by a CM that guests at the Dolphin/Swan cannot charge recreational watercraft to their resort cards (something about the Dolphin/Swan cards being on a different system).
There are a LOT of DIS-ers who are big Dolphin/Swan fans. Maybe they can add more info to help you decide.