The movie that we chose for this momentous event was Finding Dory. We figured that it was our best bet, between the bright colors and the knowledge that it didn't have too many scary moments. (Sorry, Don Bluth. We will save cartoons with nightmare fuel for when he's older)
We figured that the best thing that could happen would be he would be enraptured by the colorful adventures of the Pixar fish and sit in awe throughout the film. The worst thing that would happen is that he would freak out when the lights went out or from the crowd or something startling him in the movie.
Instead, we ended up with a middle ground. After ten minutes of trailers and twenty minutes of actual movie, he got bored and tugged on Mommy to take him out into the mall that cinema is attached to. No screaming or crying or temper tantrums. Just 'All done'
Mommy took one for the team and let Daddy and Grandma watch the rest of the movie. Which I was appreciated, since I've enjoyed most of Pixar's work. (The one comment I'll make about the movie is that the way they cashed the check they wrote with the trail of shells was beyond heart warming)
I've decided to take this as coming out ahead. He didn't make it the of most of the movie. However, it wasn't a trauma or negative experience for him. He enjoyed the time he had in the cinema. It's something to build on.