I have come to the point where I have different bags/sets of gear for different kinds of trips. For a domestic trip on a major airline on a large jet I take full frame gear (including a 600mm lens). I put this into a ThinkTank rolling bag. For international trips where I know I will face more severe size and weight restrictions, I am more and more prone to taking M43 gear, which is lighter and takes up less space. For this I usually use a GuraGear 32L bataflae. For trips with my wife that are not primarily nature photography trips, I have a pared-down rig that I carry in a 26L backpack. I always also have a "personal item" backpack for binoculars, snapshot camera, small laptop, and things I might need during the flight itself. So far I still always flown coach, occasionally with "priority boarding," but as I get older and less tolerant of long distance air travel, I can see the temptation to upgrade to a more comfortable seat. It will happen.