We're another CF family, Piper is 8, and we're in the planning process now as well! A cruise is awesome, the sea air (as you found out) is like hypertonic saline x 10! I've also heard going to the beach, ocean swimming, etc can be very helpful. As for pulling Brian out..Piper has physically attended her school only 21 days, and at this point we've pulled her out until at least March to do homebound schooling. Not sure if you've been doing homebound with him, but feel free to pm me. I can understand not wanting to pull him out, but this is a once in a lifetime trip for him..maybe check into spring break dates?