When I commute to work out in the burbs, I take my road bike, which I keep locked up in my classroom all day.
When I commute to appointments or meetings downtown (about a 5 mile trip) I take my 1978 Schwinn Suburban. It's a 10 speed with skinny tires and fenders, and I have a rack and panniers on it.
I don't like riding with a backpack, either. LOOOVE my panniers. My next bike will likely be steel with more of a touring setup. (But I'm sure it will be too darn pretty for me to feel comfortable just locking it up downtown...the Schwinn will still have its place!)
2007 Trek 5000
2009 Jamis Coda
1972 Schwinn Suburban
"I rejoice every time I see a woman ride by on a bike. It gives her a feeling of self-reliance and independence the moment she takes her seat; and away she goes, the picture of untrammelled womanhood."
Susan B. Anthony, 1896