My DD(6) and DS(3) did the Butterfly Farm tour with my in-laws in January while DH and I went diving. They LOVED the Butterfly Farm itself, but complained significantly about the bus trip. During the St. Maarten stop, the driver stopped away from down town, told them had about 30 minutes until he was going to leave again from a different point, and sent them on their way. My gang spent the 30 minutes trying to find the restroom that they had been directed to and then hustling to make the bus -- which then waited around for the stragglers! The report that I had was that the bus trip was too long and the stops were too short.
So, if you can figure a way to do the Butterfly Farm without the required bus trip, this may be appropriate. Or if your group likes looking out windows or is able to handle reading while traveling (remembering that the roads are not interstates).
Hope you have a great trip -- we leave for our $99 bonus cruise in less than 4 weeks!
Mother Grimm