Having stayed at both, I prefer the Dolphin over the Swan because it is more convenient to my family's needs (Tubbi's, Dolphin Fountain, laundry, etc.) I like simply riding the elevator and escalator down, vs. walking across the courtyard from the Swan, not that I'm lazy or anything, it's just a personal preference!
I do like the bathroom set-up at the Swan better, but there's just something about the Dolphin that wins me over!