Awesome nick. It will definitely take the whole day, and you might even need to put people up for the night. We had a LOTR EE marathon earlier this year, and, surprisingly, it didn't seem like a whole day went by. Other movie marathons we've had:

Star Wars EP I and II
Star Wars EP IV, V, and VI
Matrix Trilogy
Indy Trilogy
Aliens I, II, and III
and Harry Potter

Have fun!

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