Why watch movies? There are tons of reasons, but there is one in particular that truly is an art: quoting. But how does one rate the quotability of a movie? I have prepared a set guidelines which can used to help you.
Dialogue: Is the dialogue in the movie very accessible, are you able to use it in everyday life very, very easily? Examples of movie which have straight quotes are out there in abundance, but in my opinion the three best are Whit Stillman's Metropolitan, Bruce Robinson's Withnail and I and Noah Baumbach's Kicking and Screaming.
Watch a couple scenes from Kicking and Screaming to look at some dialogue based quotes, perhaps the easiest kind to adapt:
Timelessness: These are the movies atop all the best of lists. They are usually not quotable as a whole, but contain a few key lines. "Here's to looking at you kid," "God bless us, everyone," and "You talkin' to me?" are all good examples of this. The movie's are ingrained in our memory, thus recognizable.
Casblanca. Timeless. These quotes are ones others will recognize.

Situational: Find yourself entering (A.) a place a la Stan Mikitas Doughnuts? Perhaps in (B.) the mall? Maybe you are in (C.) an airport? All these places provide a target for a great quote. Some have less potential than others: Wayne's World is the only possible one for A. Mallrats and some other retail-based comedies can be used for B. C invites to use a plethora of movies ranging from North by Northwest to Airplane! to Catch Me If You Can to Home Alone.
If you find you find your self at Alcatraz, maybe throw in a Connery one-liner from this excellent film:

Nonsensical Situational: These usually deal with a circumstance you will never find yourself in and usually requires a friend nearby who will also get the movie, but alas these can be the most fun. Star Wars comes to mind here. Obviously one will never be involved in intergalactic warfare in a galaxy far, far away, but that shouldn't stop you from yelling "Hurry up goldenrod, or you're going to be a permanent resident!"
A prime example of nonsensical situational quote could be from The Thief of Baghdad, don't be afraid to quote yourself into fighting in a middle eastern land!