When I tour, I typically wear a long sleeved nylon trekking shirt with buttons and a collar (good for sun and bug protection). I carry a pair of light weight long trousers (for bugs in camp). I wear running shoes (and use pedals with toe clips). It's at least appropriate attire for a play or a dinner. Around home, I wear much the same, with better shoes. I'm not sure about clubbing, but why not? I guess it depends on whom you're trying to impress. All that stuff is easy to wash in a hotel sink and let dry overnight.

I only carry one pair of shorts and wash them daily, typically mid-day at a public restroom, and wear them dry. Some consider that extreme but it works fine for me and it's one way to reduce the bulk of clothing most carry.

My bike with its 25 mm tires does fine on my self-supported XC tours.