Depends on how you want to commute, by foot, by golf cart or by boat. Each has it's challenges. Your best bet to start is to find a place within walking distance and rent while you familiarize yourself with the island and look for a more permanent place to live.
The plus side of living in town is that you'll meet many more people on foot than you ever will in a golf cart. My personal opinion is that you'll become a known and accepted member of the community much sooner if you spend more time on your feet or on your bike than in a golf cart. In town will cost you more up front but you'll save on the cost of a golf cart or a boat.
There is no one specific place where expats live but Paradise Villas and Royal Palm have/had quite a few.