I recently visited Paris (rapidly unfortunately) with my wife. We did the Eiffel Tower, Le Louvre plus some sightseeing in the streets. We had a K-7 and K-01. My wife used the K-01 with the DA18-135mm. She was very happy and did not change lenses. I used the K-7 with the DA15mm Ltd and Voigtlander Nokton 58mm f1.4. Let me share my limited experience.
The surprise was the DA15mm in my opinion.
The wide angle with little distortion was perfect for street photography but also for shots from the Eiffel tower summit (see below). The DA15mm Ltd was superb outdoor both in sunny and grey (incl. rainy) weather conditions. It works well in the museum although I had to push up the ISO (not the best idea on a K-7).
The VL58mm f1.4 works well as usual and gave great shots. But the focal length was too long IMO. I should have taken my FA31mm Ltd in retrospect.
Beyond the places that we visited, and based on my previous visits at other locations in the City des Lumieres, I believe that the DA15mm Ltd completmented by the FA31mm would be a nice set of primes.
Would I use a zoom lens? I selected the primes because they are small, light and non-obstructive. I value
highly the compactness of my primes as well as their outstanding IQ. No I would not use a zoom lens, .... but my wife had the zoom lens.
Hope that the experience my interest some....