From a recent trip to Madrid/Granada, Spain and Hamburg, Germany.
When I travel overseas, there is one bag that always goes with me and that's the Lowepro Computrekker AW. I do have the Computrekker Plus AW also which can fit a 17" laptop but that wont fit in the overhead compartment or under the seat on the regional planes. Based out of Norfolk, I must always fly to a bigger city before flying out of the country and those regional planes can be small. I do bring a carry on case which I do have to check that in right before I board the plane.
With the Computrekker, Compu (meaning computer/laptop), I have quick access to my laptop without having to fully open my bag and expose the rest of the gear. WIth the laptop compartment against the back, it gives it a solid flat structure when I do have it on, which I prefer since some bags have the laptop section up front which is prone to more damage.
There's so many pockets/dividers for full customization, however Ive kept this setup since I got the bag almost 10 years ago. And after 10+ countries, its still in one piece (=
Check out Lowepro's current lineup that replaced the Computrekker.