We were looking for a Salem evening tour, spur of the moment, and happened to find Black Cat Tours. The tickets were reasonably priced and the location for the start of the tour was easy to find.
All in all, we had a GREAT time on the tour. Daniel was an amazing tour guide - he clearly knows his local history, is a wonderful storyteller, and it's obvious that his tour company is one of his passions. We learned a lot of really neat facts about Salem, haunted and otherwise, and the history lesson on the Salem witch trials was fascinating. The group was kept small, and everyone had plenty of time to ask questions (questions were encouraged), and Daniel was able to answer each question very thoroughly. He's quite funny without being corny or lame. We didn't have any children in our group, but the tour itself would probably be appropriate for children 8+ - the ghost stories are not really terrifying.
The only negative (as someone else has pointed out), is that the tour can be a bit long. The website lists the tour as being 1-1.5 hours in length (though all in all, you are walking less than a mile during that time, bring comfortable footwear as you'll be standing quite a bit). However, with all the history lessons, ghost stories, and questions, the tour did wind up being a bit over 2 hours. It wasn't a big deal for my group, as we didn't have any other evening plans, but be warned that the tour runs a bit long. On the plus side, it really gives you more bang for your buck.
Overall, we'd highly recommend this tour to anyone!