Oh man, we used to do these all the time! It was sooo boring to just walk around for hours. I was good at doing this for about 45 minutes, and then I would get bored.
We still do stroller naps if we go to a far-away museum or something and we don't have time to get home by Charlie's nap time. But thankfully we don't have to do them too often, since Charlie usually goes down for naps pretty well these days.