Hi Palomid.
I've been to Europe recently on a business trip, taking in Paris, & Brussels. I travelled light with just my X-E2, and 14mm, & 27mm lenses. This I found more than adequate for sightseeing, street & general architectural photography.
Under normal holiday visits, I may have taken either a wide angle or telephoto zoom. However I may reappraise my photographic needs after this trip; it was a joy not to be weighed down by cumbersome zooms!
Try using a couple of lightweight primes, even the X-T1, with a pancake lens will fit in an overcoat pocket, (the other pocket for 14mm, and, spare battery, & memory cards).
Use your legs to zoom in and out, and/or stitch together pano. shots to widen the view, if required.
