I would reccommend Briggs & Riley. I believe these are fully as durable as Tumi, although the name may not be quite as prestigious. The real benefit, however, is their lifetime warranty against anything, including airline damage.

The bottom line is, I don't think there is a material on earth that a case could be made of that the airlines wouldn't find a way to damage eventually. Why not have a top of the line case, but have a no-nonsense warranty to back it up?

Wow, I think I should write ads for them...lol