We are staying at The Dolphin this August....I too could not decide between the Dolphin and the Swan....what made my decision was that I read that the Dolphin is closer to the pool and since there is more rooms, hopefully, more of a chance for a free-upgrade....I would so love a balcony!
As far as the dining plan, it is something to consider. However, do you really need a sit-down table service full meal everyday? My teens are not into "dining" and one character breakfast will be enough, so after looking at all the dining choices, I feel that a table service meal everynight is more than we need.....my kids eat to live and then want to go....after a bit of research, I found there are counter-service places that seems worthwhile, good food, nice environment, good theme (check out the CS thread) and much less $$$$$ than the sit downs.
So, something to consider is how important is the sit-down dining? I do think it can add up...check the menus on all ears......pretty pricey without the dining plan.
Hope it helps!
Andrea