At my old job, I was only about 2.5 miles from work. I would run home about once a week. I, too, preferred to run home instead of to because I just got too dang sweaty, even in winter. It's cool that you have showers, so it might be cooler to run in the morning when you're fresh and have the energy. I would take my Camelbak home with me. I'd put a little water in it, and then put my keys and some other small stuff in the outside pocket. I didn't mind it, but then again, I ran 2 marathons with a Camelbak, so I don't mind running with something on my back. Some people I know just hate it.
You've got a long run there! Would you take the bus partway, or run the whole way? Good for you!