I'd be more inclined to go cheap, tape it up well, and use the money not spent on a nice bag on a small pump like a Road Morph G.
Dont forget that baggage handlers can be rough, thats why I chose our old clapped out duffel bag, same as cheap bags, I didnt worry about it getting ripped or scuffed up badly.

Oh, I thought of your plans when I read a journal recently on CGOAB. The fellow, a Brit, had done a long trip and upon his return by bike into the UK, he commented on the roads and the steepness of the hills etc

read on from here:

http://www.crazyguyonabike.com/doc/p..._id=254962&v=l

Crazy Guy on a Bike is a great source of trip journals, you might want to pop over there and look up stuff of the area you want to go.
No matter what you find, there are some fun reads, especially for us in the winter when we cant ride.