hi Kerrybelle,

I don't really have any advice about what kind of bike, but I think you'd be just as safe on a used bike that has had a good check-up from your lbs as with a new one that would need cables tightened after a short while anyway. If you're unhappy about traffic I'd say pick a comfy robust bike with decent components, not too heavy, that lets you see what's going on around you well, and spend a little money on lights, fenders, maybe a mirror and a rear rack too. I prefer commuting on my mtb because I can see more and react quicker with it and it can handle potholes and sidewalk hopping well.

Commuting by bike rocks, have fun