Welcome! Both of my children were certified at or about age 12 and both are in their late teens now. My wife is also certified and we have enjoyed diving as a family. I hope you and your son have just as rewarding of an experience! As for Bahamas, you might look into some of the live aboard boats out of Nassau. They get you away from the touristy shark dives (unless thats your thing) and off the beaten path to a greater degree. The Blackbeard/Cat Ppalu boats and the Avalon run out of the same marina (or did last June) and are easy to get to, relatively inexpensive and have years worth of experience in the Bahamas. There are other live aboards that run trips out of West Palm Beach (or used to) and the Juliet which runs trips in the Keys, Bahamas and all over the Caribbean. Several of these companies are US based, running out of Miami.
Don't forget freshwater options: river dives, cenotes, and guided cavern dives for some of the clearest waters; quarries, lakes and strip mining pits anywhere coal has been mined. When you are a new diver, you are told that 2/3 (or 3/4 depending on the cert agency) of the world is water. Don't forget that a lot of it is fresh! Good luck with your trip planning and welcome to the rest of the world!