We have stayed at both the Swan and Dolphin. We much prefer the Swan because of the beds. The"oversized" doubles at the Dolphin are not really that oversized, and as we are used to a king, it was not a picnic for DH and me! Also, our 2 DDs didn't enjoy sharing a double bed, whereas the queens at the Swan (all new Westin Heavenly beds, I might add) are fabulous.
As for the amenities, you can easily walk across the short distance from the Swan to the Dolphin, and the pool is equidistant.
We'll be at the Beach Club this time; just looking for something different!