My friend and I (we are 25 years old) purchased combo tickets for the Aquarium of the Pacific and the Ghosts and Legends Tour on the Queen Mary for $36 and we felt it was worth it.
The tour is cheesy and fun, and is slightly scary in a creepy, dark way. There wasn't much historical reference aside from a few stories about people who died aboard the ship. There are special effects in each little area you stop in, and the two tour guides were enthusiastic.
Before the show, you can tour a little art area with artifacts from the ship. From then on, you'll be called into a room to watch a little pre-show video about the ship before the tour begins.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.