Hi -
It is $25 per night for the rollaway (this I am sure of) and IIRC another $25 per night for each additional adult over 2. A possible $75 per night increase so I would call to check. Its an 800 number so no $ out of pocket. This said, for a large group I like the Dolphin as its a large room and has the sinks outside of the bathroom. We have stayed in a traditional balcony room with 2 adults and 3 kiddos so our only extra charge was for the rollaway.
I stayed in the BC with 3 adults and it was cramped, IMHO. It seemed as if the Dolphin rooms are bigger but I couldn't say for sure. Even here not all the rooms have the daybed so that could be an issue as well as the additional charge per adult over 2. Perhaps the special Swan& Dolphin rates would apply to a suite?