I agree that a good bike computer with logging would be better.
However, many people on the board cite a gps as being 10 ft or so inaccurate, and imply that means that they suck at calculating speed. That is very untrue. Successive measurements are not randomly off by 10 ft. If one measurement was off by 10ft to the north, then the next is likely to be the same. The speed is very stable.
For one reason or another, my gps is more accurate than my speedometer in my car. A bike computer should be better, but it does require some accurate measurements of tire diameter for calibration.
The real advantage of gps for the OP is that he wants the speed measurements to be stamped with a location, so that he can determine average speed as a function of position on his route to work. I'm not sure if this would be possible with a logging bike computer, but it would be more tedious at best and require writing a custom computer program. I think that a palm pilot (serial connection) would make a good logging platform for a wind meter, but I don't like this idea from the start.
Your commuting. Just try different routes, and keep track of commute times if you are trying to optimize that. After commuting for a while, most people don't seem preoccupied with shortening their commute, though. They just want it to be fun, interesting, and hassle free.