Contax bodies have gone way down in price over the last few years while the lenses have increased in price for the most part. I have always thought the Aria was a little too light. The RX is a good camera. The ST is nice. If I were to rank the bodies, I would say the RTS III is the best (it is large though) then the ST, RX, S2. If you want a small body the Aria is good.
Zeiss makes (and made) great lenses. I wouldn't call it a mystique, just higher quality with better precision. I can see the difference, and I have used practically everything, but a lot of people will swear that there is none. You won't regret getting a Contax though. Try it for yourself and you will see.
For lenses, a 28, 50 and 85 (sonnar) would be a great lightweight setup for hiking.