For me it depends on the bike. I am more likely to stand on my mountain bike and on either of my mixtes (they are single speeds so I don't really have any other option). On my road bike I gear down and spin, partly because I read that Sheldon Brown article and I am very impressionable, and partly because I feel really unstable standing on my road bike. Which is one of the things I don't like about it -- I think it is the short stem that makes standing feel sort of terrifying.