Go all the way to Paris and go to the movies? Why yes!
Paris is the cinema capital of the world. Every day in every quartier there are cinemas showing movies from countries around the world of every genre you can think of. To not take in a film while in Paris is to miss a quintessential part of being a Parisian (albeit shor-term).
To start, pick up a copy of the weekly Pariscope. It's a pocket sized magazine you'll find at every newsstand. usually issued on Wednesday, the issue costs a little less than $1.
All movies playing in Paris are listed in Pariscope. Check the table of contents and there you can see that they are organized by arrondissment (including the outlying suburbs). They are organized by genre. They are organized by title. Then they are all cross referenced so that you can turn to a page to find the number of your cinema and see the exact location, metro stop and time of your film.
Additionally, the huge shopping center of Les Halles (it has it's own Metro stop by the same name), offers two big movie theaters and each generally offer at least one new release in original version (English with French subtitles). It's centrally located, offers dining and shopping while you wait for your showtime and for this reason is the spontaneous way to catch a flick while you're away from home. There's no need to miss something you've been dying to see just because you're abroad!
A few things to remember:
1. There is a start time and there is a seance. Seance is when the film starts. The start time is when the ads start. Go for the ads! Unlike American movies where the ads are usually local insurance agents hawking their wares before the previews begin, French ads are an art form unto themselves.
2. If you don't want to see a film because you don't speak French (or polish or hungarian or any of the other dozens of languages represented each week), seek out movies marked with a "vo". this means version originale - or in the original language. They will be subtitled in French but you'll hear the original movie. Movies marked with a 'vf' are version francaise and have been dubbed in french.
3. If you are a popcorn junky, remember that most theaters offer salted and sweet popcorn but no butter topping. Try the sweet kind for a change by ordering "popcorn", for the salted kind say, "popcorn sale". As you can see, the sweet kind is the default kind you will receive if you just order popcorn.
4. Bring a few small coins to tip the theater attendant if you happen in a theater that still has one!
Enjoy.