You be surprised how chatty people get in the cockpit. As Chris said reading is probably the #1 activity, followed by crosswords, Sudoku etc. Along with that as Chris said you’d be surprised there’s actually plenty to do. I just landed in ICN (Incheon S. Korea) about 2 hrs ago. It was an almost 11 hr flight. First off when the flight time is over 8 hrs you must have an augmented crew (at least 1 additional pilot) to allow for required rest breaks for all 3 pilots. On this flight the breaks were about 3hrs each so that breaks up the flight some. We also had 2 meals (I had the oxtail soup, shrimp salad and curry chicken for my first meal and a tuna sandwich for my second). Every fix over the ocean we’re required to send a position report to the company and check our fuel, winds etc. and since we weren’t on a “route”, we had to plot our position at every fix as well. We make SelCal checks to make sure we can be contacted quickly if need be. We’re also constantly monitoring our flight path for weather (this time of year the Pacific gets some NICE typhoons and there are often storms embedded in the cloud layers). Then of course you need to prepare and brief for the arrival. Asia has many different rules than we have in the US (airspeeds, transition levels). They also often have a variety of different arrivals for different runways and you often don’t know exactly what to expect so you need to prepare for a few of them.
Put that all together and you’re lucky if you have time to read the latest issue of People