Brian, I don't use a whole lot of chain lube, 'cos on my Raven I have a Chainglider, but on my derailleur bikes I've had good luck with Squirt lube. This is a South African product, and my reasoning is that Soufafricans know lots about dry'n'dusty conditions.
(No advice on lube to help a chain during/after a high-veld thunderstorm, 'cept to avoid them at all costs -- the storms, that is.)
I think that Dan would likely suggest Purple Extreme for use in Oregon's dry'n'dusty terrain, but I've had trouble finding that lube in Eastern Ontario, where I live.
Hope that's helpful, John