I have used a Lowe Pro Road Runner AW to haul my 600 mm lens through airports for over 10 years, along with a ThinkTank Urban Disguise 70 shoulder bag for my laptop and extra lenses. Airlines have been cracking down on carry-on size and weights so here's how I'm getting around their scrutiny.
If you ditch the big and bulky lens hood that comes with the 600 mm lens and use the LensCoat TravelHood instead, everything will fit into this bag. It doesn't attract as much attention as a big roller bag and shoulder bag. The only downside is you have to carry the bag instead of rolling it. But, as I travel to bird photography locations on smaller airlines I don't have to worry about being asked to check my bag.
I recently upgraded my should bag to the Thinktank Urban Disguise 60 which is just as large as my older Urban Disguise 70, but the 60 has a place for my 13 inch MacBook Pro. I put any extra lenses I need like the 70 to 200 and the 100 to 400 mm lenses in the shoulder bag depending on which lens I decide to take. Lately, I've been taking three lenses with me, the 600 mm f/4, the 100 to 400 mm zoom and the 17 to 40 mm zoom. These three lenses are my standard setup. For my recent San Diego Workshop, I used the 70 to 200 m zoom for flight photography and left the 100 to 400 at home. This strategy worked because the birds-in-flight opportunities and the Brown Pelicans at La Jolla allow a close approach.
I'm also trying to carry less gear around, I don't feel like I have to carry everything anymore. I don't take five or six lenses to a locaton, I take the three I'll most likely use or in some cases I'll only take one or two lenses. Travel lighter, go furthert etc.
Hope this helps you in your travels.