Just came back from a tour of Spain and Italy with NEX-7 and will say that the 18-55 kit lens worked very well for almost all my shooting situations. I especially liked the OSS for low light situations, very handy in churches and museums that do not allow flash, or you just want the ambient light. Something you don't get with the primes and Zeiss...
I found that focal range worked well for most everything. I do exetensive travel and used to carry an 18-200, but after looking at most of my shots, over 2000 form all over the world in different situations, I found that I rarely went beyond 50-70mm, so it was an easy decision to lighten my load and go with a smaller focal range.
As an old Nikon shooter who used the very yummy pro level 17-55mm 2.8 I am eagerly awaiting similar quality glass for the E mount, but found the IQ with kit lens pretty good, but just to be clear I do shoot in RAW mode and process them through the Sony supplied Image Data Converter. Once you strip out the detail destroying noise reduction and restore contrast through judicious use of the DRO function the images are just about as good as those from the Nikon glass.
So that is my two cents. I would agree with other posters that one of the benefits of ILC are more lenses, but if you just want to carry one, that would be the one I would go with.