Priscilla - when we were on MUSH, about 40 of us did a private Whale Watching excursion in Juneau, I think it was Captain Larry, and we had the whole boat to ourselves. It was in the afternoon and it was absolutely wonderful, although it sounds like you have already selected RSSC excursion - my point is you will love it and its a great excursion.
Can't comment on the others as we have not done either of those, I'm sure someone will chime in with lots of good info and advice.
