Well, Irie John, you have done these things "many times" and (I believe) this is their first time so I wouldn't suggest they try saving a few bucks and take a chance of possibly ruining their vacation. I think you probably already know about the "Route Taxi" threads and how a novice visitor can have a problem there as well. Honestly, I don't do any of these things personally that I recommend as I live in Jamaica but I want to see a visitor have the best time possible.
Just the way I look at things.
I would suggest you read the thread about the Route Taxis before you just "grab a cab from the street". Think about using your airport driver or one suggested by your hotel before trying to immerse yourself in the Route Taxi business.
Again, just my opinion.
Peace and Guidance