When I lived in AZ (I know, what's winter?) I got around with nothing but a bicycle (didn't even own a car or motorcycle) for nearly 10 years, averaging right around 1000 miles/month.

Now, I commute, and will stop on the way home for groceries if they're reasonably small (less than 4-5 plastic bags worth). I am looking into getting a trailer for the bulkier stuff (my wife drinks diet soda), but usually I just drive for that. I commute probably 9 days out of 10 on average, and still go on weekend rides.