I didn't see any land when I flew to Tobago (almost the last flight of a BA DC10, now 777s on this route). Check out
Great Circle Mapper to get some idea of the route (actual routing can vary greatly, of course).
Mrs PV and I loved Tobago - wonderful beaches, nice people (and very safe compared to what I hear of some other WI locations) and amazing wildlife (I'm no twitcher, but I always travel with the bins in the hope of seeing something interesting).
Have a great time!