Get a bike that can take at least 25mm wide tires (or bigger) and have full fenders.
If it was me buying, I'd look for a nice used bike because you could get an excellent machine for $700.
Some suggestions: Specialized Tricross, Surly Pacer or CrossCheck, Soma Smoothie or Soma ES, ...Jamis have some very nice bikes too,...Kona Jake The Snake - Many of these are 'Cyclecross' bikes, but work great as road/commuter bikes. All of these are great bikes and all would take tens of thousands of miles to wear out (allowing of course for normal wear and parts replacement).