I'll note, though, that I would take having online PDF documents that we can print ourselves over having printed time tables at the airport. One thing I've taken to doing is printing out the exact pages which have the routes for a given itinerary, and then freely highlighting, circling, and otherwise marking up the pages to indicate possible alternatives.

One negative is that there are people who don't have access to computers to print out the online documents. But I posit that the people who understand travel well enough to take advantage of printed time tables are more likely than the general population to have access to computers. Another negative in the case of United's time tables is that the online versions are in fact missing some useful pages of general information which are available in the printed version (in particular, aircraft seat maps).