If you are looking for some great pants for spot and stalking any game, in your stated temperatures there are two really good ones. Sitka's Mountain Pant or First Lite's Kanab pants. First Lite's Merino Wool Kanab pants are about the quietest pants you can own. I spot and stalk western game all year long in both of these pants. I like the Sitka Mountain Pants for day hunts and I like the First Lite Kanab's for backcountry hunts where I'll be hunting in the same pants for more than 2 days, due to the awesome odor control of the merino wool kanab pants. You can learn more about the First Lite Kanab merino wool pants here:
http://www.youtube.com/watch?v=XH8OUAirg20