Hi, I’m your age and also just bring a carry-on two wheeler and a small daypack which has my purse inside it for flights & trains.
I’ve attended ballets, operas, etc. in Europe. I have a thin-fabric polyester dress that works well and also for dinners that’s easy to handwash. My second option applies for you: I always wear a pair of black pants on the plane to look nice, and because I get cold. Those paired with a flattering top (probably have something already that you wore to work) under a black cardigan and a pretty necklace & earrings, finished with black flats will be fine for any of these events and dinners. To change it up, I also bring a couple of colorful scarves, and they make me feel like I’m wearing something different. I prefer a variety of colors, so my scarves will be two completely different colors & designs. They are fine with black.
To stretch my temperature range of comfort and take up only a tiny amount of room, I bring a scoop neck black 32 degree micro-thin long sleeve top - perfect with the cardigan, your coat, under another shirt w/ your coat or by itself with a scarf for dinner. When I was in Switzerland, I also had a pair of tights to add a layer, if needed.
I bring four outfits for my European trips, plus the micro-thin layer. If your hiking is all consecutive, bring three shirts that are comfortable for hiking but could also be fine for walking around the cities. And black pants work for most anything. My shoes are a pair of Keens - the Rose style with the protective toe cap, and the lightest black flats that will be okay for evenings, etc. I’ve worn the Keens in all kinds of terrain.
I wash my clothes in the hotel sinks with the Earth Breeze laundry detergent. It looks like a dryer sheet, so it packs flat and won’t spill.
If you have a kitchen scale, weigh your shirts and pants and choose your favorites that are the lightest. They will dry faster. I’ve never purchased “travel clothes” for my dozen trips to Europe - just use what you normally wear & like. Of course, over the years when I’m looking at new clothing in a store, there’s a small voice in my head saying, “How much does it weigh?” - LOL!