For touring you can go as light as sport tourer, or use a dedicated tourer, or even an mtb. It really depends on how much stuff you're carrying, what the road conditions are, how long the trip is, etc. I've never rando'd, but I get the impression that the equipment is definitely on the lighter end of the scale, from sport tourers over to racers. Touring and randonneuring strike me as being as different from one another as they are from road racing or bmx acrobatics.