Sauna's do a nice job of dehydrating you (like a hot bath), so wouldn't recommend after a long (or hot) run/race when you should be refueling/rehydrating.
Stretching straight after and a recovery run the next day are key for muscle recovery, especially if you are trying to fit in high mileage. Also, make sure you get some protein in you 20mins after exercise, this will aid muscle recovery. Do those three things before any hot/cold treatment imho.
Edited: 15/07/2008 at 15:01