We have a shower at my work but I don't use it. I just take it easy for the last mile or two of biking and then spend a few minutes cooling off in the bathroom stall once I get there and I'm fine. Also, I wear workout clothes while I bike. I wouldn't recommend wearing your work clothes during the commute.
That's why I think everyone should bike to work if possible. It has little to no environmental impact and a positive health impact. And because you are killing two birds with one stone by exercising during your commute, you really aren't wasting any time.