Hi There,
For week-long trips in the mountains, in addition to camping gear etc, I carry a Fuji X-E1 plus 16-55 f2.8 and 55-200 zoom lenses plus a light carbon fibre tripod.
I got the 16-55 f2.8 zoom to replace the 14 + 35 + 18-55 zoom and haven't regretted it. The 16-55 zoom is very good and for me avoids the need for too many lens changes, always a pain on the trail.
I carry the X-E1 + 16-55 zoom in a LowePro case suspended from the pack straps, so it is good to go whilst walking.
Alan