Not sure what the current "theatre experience" is like in the US - it's been a while since I've visited - but here in Australia things have changed a lot over the past few years:
1. Better, bigger, reclining seats = less people in a given size of cinema. I'd guess that my local multiplex now holds 1/2 the number of people it used to per cinema, in cinemas that are the same size as they've always been. Pretty sure this has led to less noise in the cinemas - with people no longer sitting where they can whisper/yell in each other's ears, there seems to be a tendency for people to shut up as soon as the movie starts playing. And leg room, my god the leg room... - there's no way I can even touch the row in front with my feet even if I try now, whereas I used to have my knees jammed up under my chin
2. Food has gone decidedly upmarket. Yep, it's still ridiculously expensive and I normally make a quick run by the supermarket for supplies rather than spending 2 weeks' salary on a drink
3. New release movies seem to have blanket screenings, while slightly older movies linger for longer than before but generally only for 1-2 screenings per day. At any time, there's probably 3-5 new movies showing in 20+ screenings per day at a single multiplex and maybe 10 other slightly older movies doing 1-2 screenings per day. That's a change from maybe 10 newish movies showing maybe ~10 screenings per day, and nothing else. Used to be that if you missed the start of a movie's screening time by a few weeks, you'd missed your chance to see it in a cinema; currently "Rogue One" is still showing daily and it's already on DVD/BlueRay
4. Used to be that every multiplex in a chain got all the same movies at the same time; now there seems to have been a demographic shift such that "old people" locations get more "old people movie" times, and inner city gets a lot more foreign films