Thanks again for all the great suggestions! Much appreciated.
Sadly (or maybe, fortunately!) we didn't have the opportunity to try nearly as many burger options as I would have liked. Heck, I could eat a burger just about every day... my wife, on the other hand, insists on real food now and then

I *will* put it a good word for Burger Queen (the little stand across from the ferry terminal in Scarborough). Thank you, Steph, for the recommendation! If you want to grab a good burger done
Tobago style, and enjoy a bit of the local culture I highly recommend it. She opens at 7PM most nights. As Steph said, order double meat... and of COURSE have the garlic and barbecue sauce (key Tobagonian condiments).
I emphasize "Tobago style" above because, if you're from the States, this isn't likely to be exactly the burger you expect: It's made of minced beef mixed with (hmmm... I'm guessing) bread crumbs and has a soft texture. Tasty? Yes!!
I admit that part of the fun for us was parking at a random location on the street and watching the local's pleasantly surprised faces while we (two deeply tanned white folks) walked over to Burger Queen and ordered burgers. I suspect there aren't THAT many tourists who frequent the little food stalls in Scarborough

So, getting burgers from Burger Queen was highly enjoyable from both a food and a social point of view. Definitely recommended.