You know Dave, I was in Barbados two weeks ago. I had thought to rent a plane and go for a tour, but really did not pursue the idea, once I was there. There are nice scenes, but it's not that big a place, and I think you'd see them just as well during a drive around and across the middle of the island. And, it was blowing like blazes the most of the time - kinda takes the fun out of a tour flight when you spend an hour being bounced around.
I soon gave up the idea, and am happy I did.
What really made my trip? I went swimming with the sea turtles - right off the beach at the Lone Star, north end of Holetown. Choose a sunny day (so they light up, and you can see them well), take a baggy of fish scraps. Us a mask and snorkle (you really don't need fins) and swim 50M off shore from the beach at 10 AM. The turtles will find you! Be careful with the scraps of fish, you might be mobbed by these gentle creatures!
(here I am posting turtle photos on PPRuNe!)
The other thing which was well worth it, was the drive to the north point to see the waves crash up the rock cliffs, and in the blow hole down in the caves there.
My advice is that you'll remember those more (and get better photos) than getting bounced around for an hour in a rental plane!
Have a fun trip in any case....