I want to say 'you must go and see this and this and this ...' but actually
...and anyway, we're here on business and very scheduled.
As I said downstream: "Usually in the US we get commercials up until the scheduled start time, then maybe a fancy expensive ad or two (like the Sony hi-def ones that are worth watching for their own sake), and then ten-twenty minutes of previews. I actually rather enjoy the previews...
But only have reserved seating in the US in the IMAX theatres, so you have to get there early-ish to get decent seats if the movie's at all popular."