I am leaving for a few weeks in Sweden and Paris next week, so I thought I would share a few of the tips I have learned on how to travel internationally with a full set of lenses and medium format digital camera, along with laptop & all accessories.
Never check your lenses or camera, either in your luggage or on those carts you sometimes have to put your carry-on on smaller planes - never let them leave your body unless they are on the security conveyor belt or in the overhead bin or under plane seat. I always carry a smaller camera backpack that will fit under the seat of any plane, which is a last resort if all the overhead bin space is taken. Better to have no foot room rather than have to check your camera bag. With the big backpacks or roll-ons you are at risk of having to check your camera bag if all the overhead bin space is taken by the time you get on the plane. The bag that I have found works well is made by Clik Elite - it is the new Escape pack that can fit a Hasselblad H4D 40 and 3 lenses, along with various accessories. The black version looks very un-photo backpackish, so it does not scream "I am carrying expensive camera stuff". With the streamlined look of the pack I am comfortable walking with it in more urban areas and don't feel overly dorky with alot of pack straps flapping around.
Since you are allowed 2 items I also take my 17" MBP laptop in the Clik Jetpack, which has a shoulder strap and can look like a satchel instead of a backpack. It also doubles as a smaller camera backpack if needed, and can fit chargers, ipad, and other stuff to take on the plane. This & the camera back is a lot to carry through the airport but that is the burden of being a photographer I guess. Roll-ons are more convenient but come with the risk of being weighed by zealous airline staff. On one trip to France a few years ago all my carry ons were weighed, so I was busted for being over the with limit and had to check all my lenses in my hard sided porter case roll on, which was very scary. In case the airlines are weighing carry ons I now travel with a ScotteVest, which I can stuff my lenses into if needed and then put back in my backpack after going through the check in. I have the kind with the zip off sleeves that can be a vest or jacket. What I like about these jackets is they don't look like the bulky photo vests or jackets, so you can be more of an in-cognito photographer while travelling. Black is better than khaki for travelling in cognito.
Always have cf cards, battery and charger with you for camera & laptop, everything else including tripod & head goes in the checked luggage. If your luggage is lost or stolen at least you have a functioning camera & laptop.
Since I am sometimes travelling alone I always carry a Personal Locator Beacon I can set off in case of emergencies - I have never had to use it but it is comforting to have along and small enough to fit in a camera backpack.
We will be in Paris on the final day of the Tour de France, so I hope to get some fun shots of that and of Paris that I will share when we return.