chrisf,
My personal preference is that all new controllers should start out in the tower. My reasoning is that you learn aircraft characteristics, aircraft identification, and learn what your fellow tower controllers need (ex. spacing needed when it is IFR or during certain runway configurations, or Snow/Ice on the runways, or construction on the airport). Time spent working in the tower goes a long way to making you a better and more knowledgeable radar controller.
I throughly enjoy working radar more than being up in the tower, but I also enjoy being at a facility where I can spend time in the control tower looking out the windows.
Mike R
NATCA FWA