I noticed there is a big difference in fit/cut among brands. I have some First Gear pants that weren't too expensive, and have worked well for the last two years. I got the mesh pants with a removeable rain liner. In the crazy summer heat here they work fine over a pair of slacks, and in the rain they have kept me dry for short (10-60 miles) runs with the liner in.
Then, of course, there's Aerostich...