I commute every other week. If they show rain coming in the afternoon I figure I can dry off when I get home. If it is raining during the morning commute I car pool since I can't change clothes at work. I guess when I get a rain suit this will change.
If I am doing a road trip I try to ride around the rain, but I have ridden in rain when the rest of the days of the trip look good. I won't miss a good road trip just because of weather. Any ride is better than the honey-do list.