I like to decide which bike and get everything ready (gloves/jacket/cap/etc.) if it's going to be rainy. If I forget or there's unexpected weather I sometimes skip it. With rain I really try to do it, though, because the drive in and especially the drive home will be terrible. Luckily on a normal day the bike time is about the same as drive time, so I don't run into cases where I'm too late to ride in.