In a fairly flat area a hub motor would be a good option, but with hills and/or wind, I would be looking for a through-the-gears motor, which at present, pretty much means getting the Cyclone kit (given that money is also a consideration).

http://www.cyclone-usa.com/

Going 25 miles into a headwind would be equivalent to 25 miles up hill.  I would consider keeping an eye open for a used recumbent that has the potential for adding a partial fairing of some sort (could be home built but functional).  To have reliable ebike transport, meaning the ability to handle a worst case headwind, you would need something like a 60+ mile range on the flats and some streamlining. 

There is a nice speed and power calculator here:

http://www.kreuzotter.de/english/espeed.htm

You can play with many variables, including streamlining, slope, and wind, and see how much power is needed, or how fast you can expect to go for a given amount of power, figuring your contribution at about 100 watts.  The Cyclone would work most of the time, and with enough batteries, it could handle a headwind, assuming you can recharge at work.  Power used going up hill is partially recovered going down (by gravity), so its a steady headwind that would be the real killer.

Eric