Don't rule out the "nifty fifty" (RF 50mm f1.8). Smaller than the 35mm 1.8, and plenty sharp enough. You can always use manual zoom (walking)... ;-)
I do appreciate the convenience of a zoom, and I do use my 14-35 f4 as a city walkabout lens, but fixed focal length imposes a useful discipline in making you think about being in the right place. It also makes rapid "snatch" shooting - reacting to situations - quicker because it removes the need to zoom and frame.
That said, the 24-105 f4 is a great all-round lens, and if I could only carry one lens on a trip, it would be it.