Give older films a chance even if they are black and white with a (gasp!) mono sound track.
Do not always judge a film by its "deep bass rating" Taste in films, like taste in everything else, is subjective to a large degree. However it would be hard to argue with the notion that some of the worst films often have the most impressive sound effects. This can include the deepest and loudest bass too. Now, we all want to show off our new toys as soon as we get them so popping in the new Flight of The Phoenix(2004) instead of the original with James Stewart(1965) is understandable. But don't forget that many of the best films were made before anyone had ever dreamed of a LFE channel.
Here is one list worth looking at. http://www.imdb.com/chart/top
Sure you can find the occasional great film that also has a very good bass/soundtrack....Lord of the Rings, The Dark Knight, and Toy Story are just three examples. But look over this list and titles like The Godfather, 12 Angry Men, Dr. Strangelove, Antarctica, Its a Wonderful Life, The Seventh Seal, and The Grapes of Wrath are all "must see" examples of great films that you won't ever find on a "best film to demo my subwoofer with" list. And those titles are just the proverbial "drop in the bucket".
If you want to "demo" your system or subwoofer have the decency to not insult your guests with "Speedy and Serious 14". This is particularly important if the "demo" will last for more than a few minutes as *lack-of-script* induced nausea may set in quickly. Anyone following along should feel free to add their own recommendations for "must see" films that may get overlooked/forgotten in today's " 15.4" channel surround format hyperbole.
I'll kick it off with 3 of my favorites, Escape from Zahrain, Paper Moon, and On The Beach(original 1959 version though the remake in 2000 was also quite good).
Power Sound Audio