There's an annual air show in my area that usually features a B-17 and a B-24, and on a couple of different occasions I've been lying in my hammock out back when one of them flew overhead - between the noise and the distinctive silhouette it was quite the experience! [They sometimes offer rides, but the price is pretty high; I limited myself to crawling around inside the airplanes, which was impressive enough. Space is really limited, and it's hard to imagine how an entire crew could stand to be cooped up in there for so long at a stretch...]

I found a B17 News web site that includes listings for several of the active B-17s - hope it's of some interest.