bfuqua about got all the points, I'll add....
The dive op at BWI is... well... a lot of things. Understand that the vast majority of visitors to the BWI are well-heeled British bird fanciers. This is certainly the case in comparison to most visitors to Tobago, even more so on the Speyside end of the island.
You simply can not beat the BWI for creature comfort, the view and ambiance. The view of Ian Flemming's house alone is worth the price of admission. The restaurant service is predicatbly molasses slow and the quality level is not at a par with their price structure.
Breakfast however is a delight. Get up early and soak up lots of coffee and toast while feeding the tiny hovering birds off of your upheld spoon, laden with honey or jam. some other guests treated them as filthy annoyances, but for me, the magic of these little critters superceded any health fears. Life in Tobago, most certainly in Speyside, is quite slow- you're going to have some time to kill.
Their dive op, again, is geared toward their standard clientelle. Two tanks in the morning will likely take until 11:45 a.m. as they do not do multiple tank boat dives. They have the best pier (the only one in the area) and probably the nicest boats. They see most guests once a day for one tank, or one in the morning and one late afternoon. They threatened a night dive, but never delivered (on two separate trips). If you want to do four a day, it will kill you, and there will be no time for a lunch at the property, but it can be done.
To get to the bustling metropolis of Speyside, you must first hump up and over quite the entrance hill to the BWI, than as you descend back to the city lights of Speyside, it should be a 20 minute walk to the town center. Mind the trolley cars and goats.
You have entered the bustling city center plaza. It is definitely a tribal kind of place, life runs a slower pace in the last bastion of pure Rastafarian lifestyle. I find the honesty of it all quite inviting.
The first operation you will see is the one everyone knows, the Manta Lodge. If nothing else, go in and look at the exotic bar rail... it's a huge green Manta carved into the bar. It is a noisy guest house packed with divers. It has a nice efficient dive op that, like all others besides the BWI, you have an easy wade into the surf to board up their boats.
As you go along the road, and it is a road only in the sense that cars do occasionally come by, you will see Speyside Lodge, a quiet guest house of note. Right next door is my favorite dive op, RedMans. This is not for everyone. One look at the pea gravel floor of his thatch roofed hut and you'll understand. If RedMan and his son Leon decide to take you diving, they'll size you up for a few dives before they will consider taking you to their best places for hunting Mantas. Since the liveaboard showed up, they skeedaddle when divers show up because there was quite a rodeo mentality when it first began a few years ago. Now, you have to earn the chance. Where he will take you is not for the feignt of heart or those lacking in dead-on current diving skills. This is the guy who pioneered dives like
Washing Machine, Heart Attack, African Express. When I started diving with him, the only other expert was Man Friday, and he was waahed out to sea on the occasion of my second trip. Red Man is the old hand, but again- not for the "I got my AOW card so I'm all set" kind of diver. Walk in and book him when you show up. Like the "town", he's pretty
tribal as well.
I do all my night dives with him. I take my groups to him after we sort out the divers. People with a sense both of humor and for adventure~ they go with this large lovable creature.
It is in this srrip and beyond that you will find various restaurants. At lunch, be sure to arrrive in time for "hot Roti", a tradition from the slave days that wraps a tortilla shell around Garbanzo beans, curry sauce and those typical indecipherable pieces of Caribbean Clucker. Yummy.
The closest grocery is waaaaaay over the twisty switchbacks that divide the NE from the NW tip. In Charlottesville it does well because this area is the only place for large yachts to drop anchor and re-provision.
Most Caribbean islands I counsel absolutely against driving a rental car. I make the exception for Tobago. This island is meant to be explored. The trip alone from the airport is two hours, and the rental of a Samurai for the week comes close to offsetting the cab ride transfer from the airport. The roads are superb but not illuminated or reflectorized, there are precipitous cliffs and switchbacks, but if you go slow like I do, you'll likely enjoy the versatility of that Samurai.
Really- rent a car.