From a KC-135 guy, we def. prefer refueling the C-17's vs. the C-5's 'cause you guys have an 80% chance of showing up on time where as FRED is about 50% (I think I'm being generous on that one)...HOWEVER, anytime it's 2am over the Atlantic and the receiver pilot says, "This is gonna be my first real operational A/R", it doesn't matter what he's flying, my hands are on the throttles, ready for the br&akaway...
When I was an airline guy (CRJ's so no long legs), I would always go "help the F/A's clean up the cabin" after the first leg of a trip so I could grab a USA today (clearly written for pilots with the color pics and short articles), local paper, and a few magazines, kept me sane for a couple of days...like someone else said, unless you are in Indy center where they have you switch freqs. every 4 seconds, you can usually get some time in to read (unless your company forbids this). In the tanker, I read until I get sleepy, then I take a nap, then I wake up hungry and eat, then I get up to pee, then I just repeat the cycle multiple times until arriving at my destination. 2 pilots, and 10-15 hour legs...although I have thrown a football in the back with some crew chiefs while killing time over the Pacific...