I think now is probably a good time for the men replying to this thread to stop projecting their own feeling of safety and comfort on the lady that created this thread. We're not able to walk a mile in your shoes on this one so the sooner the guys replying to this thread acknowledge that the better. That's just a simple fact.
Now, let's start discussing the topic here.
I commute to work and know two women that I occasionally have commuted to/from work with. They both usually coordinate their rides so that they are not riding alone. I can certainly understand. Riding with a partner has a lot of benefits beyond just personal safety (e.g. having someone to chat with while you're fixing a flat!). I'll ask them the next chance I get so I can get some insight into what some of their fears are.
I like some of the responses I've seen. We each deal with risk everyday. The objective is to take the steps necessary to reduce that risk as much as possible.
Perhaps you could reexamine the route you take. I certainly like the idea of being unpredictable. Most certainly, you should be riding and be quite aware of your surroundings - just as you would if you were walking. If you know someone in law enforcement perhaps you could get their perspective on some of the areas you cycle in. You may find that they're not nearly as dangerous as they appear.
Pepper spray is probably not a bad idea even though it may provide more of a psychological protection rather than being a true physical protective device. That said, if using it gave you a few moments to make an escape it would obviously be worth it! Like anything, you'd need to be careful that you don't end up on the receiving end of something like that.