I love watching the trailers before a movie. Usually there are commercials before the trailers but only one or two, so a couple of minutes worth, then two to three trailer which takes up another 4 to 6 minutes. That's it.
I love love love trailers but hate the 10 minutes of adverts you're also subjected to. I have friends who like to arrive to the cinema exactly as the film Starts but us hate this as I'd miss the trailers. At my cinema it's often 3-4 trailers, so about 8 minutes or so.
This is the reason I DON'T go to the movies!! When I've won movie tickets I find out when the actually film is going to start, so I can wait outside the theatre until then! The theatre we go to view 'arthouse' films, only has the movie, as it;s in our wonderful local art gallery..