Do you have hills/bridges on your commute? If you don't need gears, then the giant via looks like a nice bike (with fenders) at that price point:
http://www.giant-bicycles.com/en-us/....w/9050/48941/

There are lots of other good bikes, but at that price, most will be without fenders and other such commuting niceties. Alternately, you can buy fenders later, like I plan to
Almost all the big names, Trek, Giant, Specialized, Raleigh, Jamis have step through bikes - and at that price, the difference between them isn't much. Try as many as you can, and choose the one that feels right.

Edited to add: the Via has gears in the higher models.