I quite often need to have my car at work, so I do the half commute thing. I drive into work with my bike on my car and then commute home that evening. Then I bike back in the next day, throw my bike on my car, and then drive home that evening. Then repeat!

This works for me for a number of reasons:
1) I always have a car at work if I need to go to meetings in other buildings
2) I have a place to lock my bike (we don't have racks...though I can't imagine why not since biking is so big with my company)
3) I can keep my day 2 clothing nicely hanging in my car
4) I can bring in toiletries, extra lunches, extra shoes, etc...when I do the drive part of the commute.

I'd love to commute both ways, but needing a car at work and having a 14 mile hilly route, makes it tough. Plus, to avoid traffic, I also try to commute very early in the AM or very late in the PM so if I did both ways on one day, that would mean that I always worked 10-11 hour days. Yuck!

Oh, and we have a gym/locker room at work, so I can shower easily enough.