Hi Babie,
I'm late responding to this thread but I like your thinking of a Mixte. I have built many of them for myself and for houseguest to ride and have so much fun riding them, they're always the first bikes to grab out of the bike room.
I agree with what others have said and you already have done your homework on models but I have had very similar Peugeot's mixte frames that had tremendous weight differences in the frame alone between them even though they looked identical; I had two framesets unbuilt at the same time and could easily feel the difference. It was all in the tubes they used, they both looked the same, models, lugs and graphics but one was significantly heavier than the other. They are generally good quality mixte's and fun to ride but just make sure it's one of the light ones. Also, make sure it has a good wheelset, many mixte's came with heavy cheap rims, a good light wheelset and tires make a big and noticeable difference and more fun to ride. While there's quite a few step-through bikes available in Zurich, I definitely recommend the two top tubes running down to the rear dropouts style mixte frame (like the Peugeot), they're much stiffer and longer lasting frames that can handle a heavy rider and take abuse from previous owners. I also recommend when test riding the bike to see how well it rides with no hands on handle bars, I found many of these used frames were not aligned very well and could not ride straight with hands off the handle bars. Buying a good complete Mixte is recommended as they're not easy bikes to find parts for and can get quite expensive getting the correct parts, especially the ones with uncommon threads for bottom bracket and headset. I am 183cm tall and have had no problem riding different sized mixte frames, I would just build them with a tall stem and different bars to get a comfortable riding position and still ride great.
I also recommend looking on Facebook Marketplace for bikes in Zurich, you'll be surprised how many bikes for sale and cheap nearby you.
I wish I could find photo's of my old Peugeots but could only find these two pics of my Univega's. Here in Venice Beach it's very flat, no hills and easy riding so I opted for a very simple rebuild to keep them light with only one gear, no fenders but I could definitely see needing gears & fenders to commute through Zurich. I could also see hopping on a mixte in the summer riding down to
Flussbad Au-Höngg to jump in for a swim or riding to one of the lakeside bars to meet friends for a drink on a hot summer evening, the ride home is always fun!
