shotthebreeze:... celebratory dive trip in September/October ... decently priced, perfect for a beginner diver. I'm thinking the Florida Keys
Good thought about watching the weather. If you go mid-October you should be in great shape. Echo the Key Largo suggestion - great, shallow, warm reef diving out of Largo, perfect for new divers. Get a direct Boston to Miami flight, with a reasonably short drive to Largo from Miami. Many good operators in Largo. You might wish to check some websites, and contact them in advance to get a subjective 'feel' for them. I might suggest Ocean Divers myself, but you won't go wrong with most of them.