I rarely go to movies anymore just because of the cost, Netflix streaming to my TV, plus the fact that with 3 kids it is cheaper to just buy the DVD makes theatres a rare occurance for me.
Since a few others have posted about kids and what they did at movie theatres, I'll drop my cute story here.
My son was about 5 when Star Wars Episode 2 came out, he is a huge Star Wars fan (as are his parents) so we all went together for opening night, with some friends for the 7 pm show (so DS wouldn't be up too late). We spent the day discussing theatre behavior, and how he was going to sit between mom and I and he could whisper us questions, but no louder than a whisper.
We got to the movie and got good seats, on an aisle so if we needed to leave we wouldn't bother others. The movie engrosssed him, I had never seen him sit silently for almost 2 hours. Then the scene where Yoda pulled out his lightsaber to battle Dooku came on, there was a gasp from the whole crowd, and then from next to me "MOMDADYODAHASALIGHTSABER, YODAHASALIGHTSABERLOOKMOMDADYODAHASALIGHTSABER" In the most excited voice you can imagine. I was super embarrassed for about 15 seconds, and then the entire theatre broke into laughter because it was obvious that DS was just so into the movie and the character.
One of my favorite movie-going memories.