I guess it depends on the commute.
My commute in is 2 miles. The first mile is downhill and the second mile is pretty flat. So I just (try to) take 'er easy on the way in. Just a little sweat patch on my back when I arrive.
On the ride home I also take it easy, but end up sweatier, esp. when it's warm out. But I'll be home before it gets bad and just take my daily shower at that point.
I keep zero bike stuff at work. In the winter or when it might rain in the afternoon, I keep rain pants in my backpack.