I booked a chocolate tasting tour with Tasty Tours at the last minute after another tour company (Best Tours) screwed up our birthday plans. Audrey was incredibly nice and prompt in her communication during the booking process.
As for the tour, we visited unique chocolatiers, bakeries, and even an unexpected location (you'll see when you are on the tour) throughout King West and Trinity Bellwoods. The chocolate was excellent and our tour guide Alex did a great job explaining the history of chocolate, the manufacturing process, and the what we were tasting. Our group really enjoyed the variety of the stops, tastings, and the ability to see new parts of the city (even though some of us were from Toronto!). Just make sure you wear walking shoes :)
I would love to get into more detail but don't want to spoil it for you. Just book the tour because it is a great value and the other reviews show just how many people feel the same way.