They are both in an excellent location, so they're equal on that count. The Swan is just a bit smaller, hence, a bit more intimate. I believe they also have some rooms with the 'Heavenly Bed', that soft, wonderful covering that makes you feel like you're sleeping on air.
The Dolphin is a bit bigger, which is not necessarily a drawback, but I don't think they have the cozy bed. Given that, I'd opt for the Swan, if you're not particular either way.