Depends a bit on my destination and mode of travel. I carried my Canon A-1 with the cheapo 35-70 f/3.5-4.5 along with the 50mm f/1.4 (both about the same size) along with an Elph Jr APS camera for snapshots on a two week trip to Italy. Light and compact. If I had been more photo-oriented and could stand more bulk and weight, my 35-105 f/3.5 would replace the 35-70, but that bigger zoom is large and heavy.
Unless my trek was totally about taking pictures (including no family/friends to provide constant distraction), I can't imagine dealing with a half dozen different lenses.