Hi, Shawn! Thanks for bringing your question to the Disney Parks Moms Panel.
Fantasmic! and
Star Wars: A Galactic Spectacular are both incredible shows that I think every guest should experience. That being said, it is difficult to experience them both on the same night. Fantasmic! has a duration of 30 minutes, so the show will just be ending as Star Wars: A Galactic Spectacular is starting. The amphitheater in which Fantasmic! is performed can accommodate quite a large number of guests, so sometimes it can take some time for the crowd to make their way out of the amphitheater and down Sunset Boulevard at the conclusion of the show.
If you have time to visit
Disney's Hollywood Studios on two separate evenings, then I would recommend experiencing these shows on different nights. If your trip itinerary cannot accommodate two visits, you might have to choose the show which interests your family more. I know that decision seems impossible! If you really cannot choose between these two amazing experiences, I would advise you to watch Fantasmic! from the back of the amphitheater in the standing room only section. You could then sneak out during the finale of the show and make your way over to Hollywood Boulevard to view Star Wars: A Galactic Spectacular. You might miss the first couple minutes of the show, but I think this plan would allow you to catch most of it.
Shawn, the good news is you really can't go wrong either way. I think you will enjoy either one of these nighttime spectaculars immensely. Wishing you a magical Walt Disney World Resort vacation!
Samantha