My wife and I have been on a ghost tour before in Savannah, but that was nearly 20 years ago. Even so, we were interested in doing another one with our 14-year old son.
(Note: he loved all aspects of it, and even had questions that were answered at the end of the tour, but email them in advance with any questions, and you can decide if it would be a good fit for your teen. If your teen doesn't have a long attention span and would rather just hang out on social media, this is probably not a tour they would fully appreciate). Our son had completed an honors course in Georgia History last year and actually knew more about Savannah than my wife and I did, so he was a ready and willing participant on this tour.
We opted for this tour because it added the slight twist of letting participants use an EMF tracker to detect paranormal activity. While I personally harbor a healthy amount of doubts about whether or not the technology is detecting paranormal activity or something else, there is no doubting that our tour guide, Patrick, presented an awesome experience with plenty of historical information about Savannah and it's ghostly past, and for that reason alone, this tour is worth it. If you've watched the ghost hunter shows on TV, you'll love the inclusion of this device. The tour was easily two and half hours and Patrick hung around to answer any lingering questions that we had. He's been doing this tour for 15-20 years, so you're probably not going to find a better source of information than what this tour offers. Many of the other ghost tours (and you'll see them out and about at night if you wander around the historical squares at night) are led by college students and honestly, the students running them just don't have the same experience or personal knowledge of the guys running this tour.
Don't hesitate to book this tour. It's priced right, takes you to many of the areas of haunted Savannah (all outside), and the EMF detectors are a nice added touch.