Kevin- I would definitely go with the Insulator Stabilyx tight. The material itself is a Nanotech fabric that regulates heat close to your skin depending on temperature. For example, if you are out in the AM for a run and it's 30 degrees outside, the material will form a thermal layer and prevent heat from escaping until you reach about 78 degrees at your skin surface. This is the optimal temp for muscle performance. Then the material will stat releasing heat and keeping you at that level point. So the tights don't feel hot. Also, there is a wind blocking material on the quads which is great if the cold PA winds pick. I think you will be really pleased with the Insulator Stabilyx. Plus if you ski, you can use it as a base layer for skiing. I would go with a medium for the size. Good luck.