[williswall]

With my latest Bday gift of the Leica M43 50-200mm lens, I believe I am set for just about any of my travel photography needs with this series of Optical Image Stabilized lenses working in concert with my Panasonic G9....plus all are weather sealed and accept standard screw on filters. Blog write up here with samples.

[InFlight]

There is a newer very pricy Leica 10-25mm f/1.7 wide zoom.  With the 2x crop factor its hard to go really wide without a fisheye.

On the wide-end I generally prefer a fast prime over a zoom.  The Leica 15mm f/1.7 would be a good choice.

[williswall]

I do have the Lumix 20mm/1.7 pancake lens....haven't used it much but it's wonderfully compact and light and gets good reviews for quality. I may use this more often when size is critical. My only real complaint is the noise when it's auto focusing, not good for video.