If you're thinking of Zeiss optics, and are looking at a rangefinder, seriously consider the Contax G2. Brilliant camera, brilliant optics. They're actually some of the very best optics ever made for 35mm. I have the 45 f2, 35 f2, 90 f2.8, 28 f2.8, and 21 f2.8 lenses. They are all super sharp even wide open, with the exception being the 35. It's still a great lens, but it falls short in comparison to the rest of them. I'll post a scan of a shot I took with the 21, hand-held, wide open at around 1 second. It is of Gaudi's plaster model workshop in the crypt level of the Sagrada Familia cathedral in Barcelona. Most of the room is white from the plaster models. The image was shot through a sheet of plexiglass. I've had the print enlarged to a 12x18 and it still looks great. Film was Fuji Reala 100.
The G2 has become my primary travel camera. I've taken it with me to Argentina, Puerto Rico, and Spain. All the Puerto Rico shots in my gallery here were taken with the G2, if you want to get a better idea. Oh, and the Puerto Rico shots were all done on Ektar 100.