In reply to shaunnorfolk:
Loads, depends really on where in the SW you will be, when in the year, and for how long.
Pfalz sandstone towers, Gueberschwier just over the border from Freiburg in Alsace, the upper Danube valley limestone just East of the Black forest, Battert, come to mind.
If you have a bit more time, you could even try the Swiss Jura or limestone Alps (not more than a couple of hours from the Black Forest).
CB