Are you tying it into the family charter or making 2 separate trips. Full disclosure, I always think longer is better but with only 5 days I would make sure to consider things like...

What if you have a flight delay?
What if something happens with the boat that needs a maintenance call which would cut into your itinerary plans?
How far do you have to travel to get there? For us it is a full travel day each way, typically about 20 hours from door to door. I need recovery time on each end!