Traveling with the 5DM3, GPS, 24-70 f/2.8, Eye-Fi Card and rambling on. . . .
/I recently returned from 8 days in Costa Rica/Panama and I wanted to share some thoughts- Here are the "highlights" of my ramblings in this video1. Dual Card slots in the 5D Mark III are really nice - I shot Full RAW to 32GB CF cards (SanDisk Extreme) and small JPEG to the Eye-Fi card (16GB X2). Using the Eye-fi's direct mode I was able to easily and without issue share selected images via the rate function to a Nexus 7. Previous eye-fi cards/firmware I found direct mode to be buggy but it was really solid this trip. On the Nexus I used PhotoGrid HD to create collages of 3-4 images and shared those to Facebook.
2. The Nexus and my 5D Mark III fit snuggly in a Vanguard 18 Bag. I didn't always carry the nexus with me and if I wanted to keep the GPS logger attached to the camera I can remove the internal padding in the Vanguard and it fits. Because I use a lens hood instead of a UV filter I can put the camera lens down in the bag and not get the end of the lens covered in sandy bits. I didn't even bring a camera strap (confession I forgot it at home) but using the Vanguard was preferable. The camera was out of site unless I was holding it. The top zipper seam on the Vanguard makes it very easy to "drop" the camera into the bag and ZIP. . it's gone.3. I enjoy the quality and value you can get with a prime lens - said another way I have never been a fan of "do-it-all" lenses like the 18-200. This trip has changed my opinion. . . some. I certainly wanted nice photos but I was not willing to carry a ton of gear, either because I didn't want to look like a walking target for theives or I just didn't want to lug around a ton of gear, mostly the last. I spent most of my time shooting with the 24-70 f/2.8 Mark II and brought along the 70-300 IS USM for longer wildlife shots. I have since played with the new 24-70 F/4 IS with Macro mode and I would have rather taken that - the f/2.8 is only marginally useful for vacation type shots and the IS plus the macro mode would have been a welcome addition in several instances. Another option for me would be the 24-105 - quite a nice range. For crop sensor shooters using cameras like the T4i (650D) the 18-135 would have been a fantastic lens. 
4. I used the GPS logger from Canon (GP-E2) and it worked VERY well. 95% of my photos are already tagged. Battery life of the unit was excellent and it was quick to get a lock. There does seem to be an invisible action that causes the camera battery to drain. I often leave my camera on overnight and on this trip I would find the battery dead in the morning IF I had also left the GPS logger on. The simple solution is to turn the GPS and or the camera off when you are not using it.
