If, like me, you love shooting wide, the Lumix S 14-28mm would be a brilliant choice. I'm currently in China, I brought my recently purchased Lumix S 18mm F1.8 with me so I could claim back the sales Tax, but I would have no hesitation in bringing just the 14-28mm as an only lens. I was in New Zealand for 3 weeks or so earlier this year, the 14-28mm hardly came off the camera.
As I wrote, If I could only take one lens, the 14-28mm would be my choice. I even took it swimming with me, there's a thread on here about that

So versatile, it's weather sealed, light, small and compact, sharp, and not stupid slow. Highly, highly recommended.