Up to a century, plus/minus, I can use any of my rides (which are all pre 85'ish), but beyond that? My experience here is limited, although I must believe that the 'randonneur' inspired bikes are the ticket. With this I mean longer wheelbase, raised handlebars, luggage and bottle mods, etc.
I would also focus on less techy, simpler and more fool proof components, such as friction shifting, toe clips, loose ball BB's. But I would definitely use a cassette hub.
This is what I'm working on these days:
