Hey this is a nice thread but can I request you add something to the OP? The expiration dates are MUCH sooner than printed. For instance, the priest ticket at the end of the month is 7/31. However, if you try to use it now it will not go through because it is no longer showing at theatres. The actual expirations for all these 'free tickets' are not the printed dates but whenever they stop showing the movie. I printed one of the priest ones and went to the ticket counter and the guy told me since they are not showing priest any more they can not take the ticket. Sucks but it is what it is.
Unfortunately it's impossible to predict when a movie will be leaving your local theaters, as it's usually based on demand. Priest is gone here too, well before the movie cash has run out, but it may well still be playing in other theaters elsewhere. At the same time, the Hangover 2 movie cash just passed its expiration date and that movie is still playing on two screens at the theater that I usually go to.
Basically, you do have to use some common sense with it -- if the movie isn't doing particularly well, or if there are a ton of other newer, hotter movies coming out (I mean, how do you even expect Priest to compete with X-Men, Pirates, etc.?), then it's not going to be around as long. Even more so if you live in a smaller area with less theaters. It should also be common sense (even if you didn't bother to read the ticket, where it's clearly stated) that once the movie in question is gone, the movie cash for it will no longer be valid either (technically, the theater isn't supposed to be accepting it for other movies, even if they will do so).
Basically, when you get movie cash, you shouldn't just sit on it indefinitely. If a movie is doing well, you're probably ok waiting a little while, but if there are signs that the movie is dying off, you should make sure to use it while you still can.