I have to say in defence of Boathaven Bay resort when I was there....the views were bad, but the accomodation and staff were top notch. Staff were brilliant for booking tours arranging activities and for the cruise we went on, we were picked up outside the gate. it was one of the nicest places I stayed in, (we had hot tub on balcony) and if I were going I would stay there again, views being the only negative, so I hope I did not come across as slating the place. Have a look at tripadvisor for accomodation around the Airlie Beach area, there are photos of Boathaven Bay and the views that were to what they are now.
It is funny how people had differing views, it is good your sister liked Daydream Island, I definitely thought it was beautiful, but the outdoor chapel had a dirty manky red carpet and I just thought it was corny. I did not stay in the resort accomodation, so cant make any comments about the standards.
Islands are expensive for accomodation and in my opinion not worth it. Yes I would think it is possible to get the watersports etc even if you do not book an inclusive resort. One thing that did strike me about the area was the numerous tourist activities very widely available.
If you email one of the tourist outlets, plenty on google, they will get back to you and direct you re activities, etc.
Did I tell you already I am so jealous. I probably did.