
I can definately vouch for getting up and having a stretch/walk every hour or so. On an overnight flight from Orlando last year I slept for pretty much the whole flight. This sounds great, but I had a real struggle to get my feet back in my shoes as they had swollen up loads! A really weird feeling but eased up after an hour or so after landing.
Once you've booked your ticket and know what airline you'll be flying with, you can work out what aircraft type will be used, and ask for a particular seat. See here for an example of a Virgin 744 configuration: http://www.seatguru.com/airlines/Virgin ... -400_1.php
Generally, once on 'the cruise' I tend to alternate between reading/iPod for a bit, then watching some TV/films, it's great if the plane has got AVOD (Audio Video On Demand), but even the older aircraft types give you a good choice of something to watch. Whatever you do, don't bring up the display which shows the progress of the aircraft on the route and the predicted arrival time - it's a soul destroying thing to see you've still got another 7 hours to go!