Each year we go through the same drill, the old 1976 23' Slickcraft ss235 is really getting on in age and it would be nice to replace it.
The old boat does have some qualities that I suggest you would want for an island boat:
1. Good in foul weather - cuddy cabin to keep all that gear/tools dry, a lot of freeboard, canvas or roof overhead when running in rain, windshield wipers.
2. Good utility boat - can carry lumber (cabin door in center to accommodate long items), shingles (heavy), refrigerators, wood stoves and a load of overweight relatives/friends. A lot of open space in the back as opposed to wrap around seating with cup holders and stereo speakers.
I would suggest nothing smaller that 22' to 23'.
We have looked at the Eastern 22' model and that may be a solution when the old boat dies. There are a few on then on the lake. See:
http://www.easternboats.com/boats/eastern_22.php