I don't think either is really more kid-"friendly"....but you might find the Dolphin more convenient as a parent because:
1) the laundromat is in the Dolphin
2) Tubbi's the 24 hour "buffeteria"/convenience store is in the Dolphin
The Dolphin is bigger, more of a "wow" lobby, the Swan has a more understated ambience.
The standard Swan room has a second sink/vanity area outside the actual bathroom which may be convenient with multiple kids/people in the room.
The beds at the Swan are queen where at Dolphin they are oversized doubles.
The Grotto pool shared by the two hotels is a TAD closer to the Dolphin than the Swan (if you are located in the west wing of the Dolphin).
DH and I and the teens (and former teens) in our family prefer the Dolphin....but that being said: we spent a week in January at the Swan with DH and DD (18) and I in one room, and DS and DIL and 2 grandbabies ( 3 yrs and 18 mos) in another...and we all had a perfectly wonderful time
