When flying halfway around the globe, it goes without saying that you don't want to be in coach. Sometimes it's unavoidable, but having a good seat (and good neighbors) can make the difference between a mildly uncomfortable thirteen hours and the most miserable day you've ever had. Before I was a airline regular, I used to think that Business and First class seats were for the wealthy. Now I know better. Modern day premium seat upgrades are a perk given to frequent flyers, often at no cost to the traveller. To get the upgrade, sometimes you just have to be nice to the ticket agent when checking-in. Other times, you'll have to ask for it. If you spend more time on a plane then any human should, you already know this, but having a Business class ticket also grants you access to the airline's Admiral/Executive lounge, which has clean bathrooms and complementary snacks and beverages.
For my flight today I made a quick checklist of what to bring on-board to maintain sanity:
PowerBook, DVD's, and the all-important air/auto power adapter. (I use one by Lind and have no complaints about it. I think I got it at an Apple Store.) Premium seats all have power outlets, but if you're in coach you'll need to ask about power when you check-in. Hopefully the ticket agent will be kind enough to move you to a seat with an outlet. For power on land, I also brought the relevant outlet adapters for the countries I'll be in.
A fully-charged iPod
A charged N-Gage QD and a couple games. (I'm still playing The Sims.) The N-Gage has an "Offline mode" (it's actually a "Profile") that turns the radio hardware off. You must take the device offline to use it on a plane. FYI, the original N-Gage is tri-band GSM, so it will work on EU and US mobile networks; However, the QD is regional-only, so you'll need a back-up device when traveling abroad. I packed a Nokia 6600 for voice/data.
A neck pillow. These are annoying to carry around, but worth it.
A physical book. You can't run electronics all the time, so an actual printed book comes in handy. For this trip, I'm still working on "A Short History of Nearly Everything" by Bill Bryson.)
Additional reading in PDF's in case you finish your book. I brought "We The Media", which was released under a Creative Commons license.
Bottled water. In Business class they hand out bottles of water, but just in case the dice don't roll in your favor, having your own water on hand is important.
Headphones. In addition to water, Business class travellers on international flights also get complementary Bose noise-cancelling headsets for the flight; However, I don't care for them. Something about the sound-cancelling process makes my ears feel like I've been listening to really loud music without the sensation of hearing really loud music. Sounds odd, I know. Instead of cancelling sound, I use a set of Sony ear-buds that physically block sound, like having a speaker inside an ear-plug. The design has a soft rubber cone that seals in your ear, cutting out a tremendous amount of background noise, and functions equally well as comfortable ear-plugs. If you're going to be ultra-hip you'll have to order these from Japan so you can get them in white to match your iPod. Mine are black, purchased from one of the Apple Stores. The Sony Style store in the Metreon only carries them in black as well.