To each his own.
I love taking the boat over, my dive buddy likes to fly!
Since people are arriving at various times they could take various transportation options.
For people who value time above money (type A's) and are in a hurry to BE THERE, instead of getting there, the plane from the international airport is the answer.
For the laid back type who want to mingle with the locals as soon as possible the boat is the answer. 3 to 4 people can share a taxi to the boat dock and the boat is the least expensive way to get to the island.
In-between would be for a group to take a taxi to the muni airport then fly over. They would get a ride through town and the plane costs 1/2 of what it does from the international.
Just be sure you have timelines right before you make arrangements.
Personally, I like to take the ride through town and take the boat full of local people. I feel like I am THERE as soon as I walk out into the clear, clean air at the airport.
When it's time to go home I prefer to fly directly to the international. I don't have to handle my bags from one plane to another.
I take groups on trips and you deserve lots of love for doing this thankless job.
Good luck! Enjoy!