Welcome to ScubaBoard. While Tobago doesn't show up a lot in trip reports, I see people ask about it every once in awhile. IIRC, one of our members indicated there's some brisk drift diving there? It's also my understand travel to/from Tobago may be a bit time consuming and/or expensive for U.S. folks.
A number of U.S. divers have an interest in not-too-distance places beyond 'the usual suspects' (e.g.: Cozumel, Belize, Bonaire, Roatan, Florida Keys), and Tobago's close enough to warrant a look.
Maybe you can post us some trip reports.