I'm a cycle commuter, so my favorite distance is the minimum safe distance to get from point A to point B (which aren't always that close).
Eugene to Portland puts me at a minimum of about 140 miles, and a maximum (so far) of about 200 miles for a good day trip.
I regret to admit that it took me a day and a half to get to Crater Lake, but there was some wicked hill climbing getting up there. Maybe next time I'll make it in a day.
I think I did about 9 century+ rides last year, and almost all of them were long commutes.