I've been on the USS Drum, USS Becuna and the USS Cobia. The Cobia (Wisconsin Maritime Museum, Manitowoc, WI) was the best experience of the three due to the fact that the tour could only be made with a museum employee. It could not be boarded without a guide to supervise, which means nobody could trash the interior. There were no self-guiding plaques and only one plexiglass barrier (radio room), so it all had an authentic appearance and made for good picture-taking.
You can check out my pictures here:
http://members.tcq.net/nzeronv/cobia/
-Jack-