Most of my hiking is summer hiking in Oregon, so it fits your warm/cool profile. I generally wear REI Sahara convertible pants. They work for me. But then, anything similar would probably work just as well.

With convertible pants, the thing to watch for are where the seams hit your thighs, and any signs of poor finish-work there that might irritate your skin as you walk. Other than that, the ease of taking the lower pant legs on and off while you're wearing footwear.