It all depends on the aircraft that you're flying, but remember that a lot of cockpits don't have room for too big a bag to be stowed anyway: and the baggage compartments aren't always empty, either!
I wish that I'd kept the old RN pilot's nav bag, but if I'm not toting a helmet bag then I tend toward an old backpack which can be scrunched up and stuffed in a small corner. After the contents have been carefully distributed around the available space before take off
ps since the type of notebook has become part of the topic, an MB Air with tethering through the iPhone has to be the Bee's Knees these days: and saves a fortune on hotel internet costs
