I shipped the following as checked luggage in their original shipping cartons: PowerMac G5 tower, 20" Cinema Display and 17" Studio Display. All arrived without incident via SFO/DFW/LGW/VLC back in 2005. My friend worked at Apple and guaranteed that the original shipping box/packaging was the best option. It is tested for air handling, drop tested, etc.

One trick that may have helped was that I wrapped the boxes in shelf paper, you can find some that is plain light brown like cardboard, so that at least from a distance, they weren't obviously computers/displays. Maybe this helps a little on the theft angle. You can write "FRAGILE" all over the outside just to alert the handlers in case that helps too. Lucky for you the Apple packaging is a lot more compact these days - my boxes were huge!

The crazy thing was that due to weather, we were stuck in DFW for 24 hours so those items were sitting around in some baggage area under the AA terminals all that time but still made it no problem. It was hard to sleep that night thinking about it!

I had checked around for additional insurance, etc., but nothing existed. However, I found out later that my homeowner's insurance might have covered theft or damage. Since I was renting out my home, I still had that coverage for 30 days after moving out. Make sure you back everything up and password-protect your system just in case. Good luck!