The first and only Star Trek movie I've seen in the theater was Star Trek VI: The Undiscovered Country when I was 11. It was actually my introduction to Star Trek. I knew of the show/films, knew who Kirk and Spock were and all of that but I'd never actually watched it. I was at the mall with my mom and her friend and they decided they were going to see Ghost, I was given the choice of either seeing that or the only other movie starting around the same time, Star Trek VI. I wasn't exactly excited, but it seemed like a better choice than whatever chick flick they were going to see, and being a huge Star Wars fan I figured anything with spaceships would be better. I loved it though, I was an instant fan. And I like to think Captain Kirk saved me from having the awkward experience of sitting though the Ghost love scene with my mother and her friend. Kirk saved more than the Federation that day I assure you.
While I became a big Trek fan, it was only the TOS stuff (which ended with that film so I was late to the party), it wasn't until many years later that I gave TNG a shot and by then all the films had already been released. The new stuff I've just waited for the DVD/Blu Ray, as I barely go to the theater anymore except for James Bond movies and I went to see Star Wars.