I am focusing on exercise, primarily by walking for at least 30 minutes each day, although my current goal is 50 minutes. Walking is easy during the spring, summer, and fall, but is a challenge during the winter.
My goal is to keep walking this winter, which means I need some clothes, particularly pants, that I can put on to keep my legs dry and warm. I have good boots, jackets, gloves, etc..
How does one buy snow pants? I assume they need to be large enough to wear over pants or sweats and ideally they should be easy to put on and take off. I don't want to spend 20 minutes getting dressed for a ten minute walk!
This site 
says a rule of thumb is one size larger than your pant size.
The North Face Freedom Pant looks promising. There is a North Face store near me. Here is a link to the product page on North Face's web site. Dick's Sporting goods has the North Face Men's Seymore that is cheaper than the Freedom Pant.
On the other hand, the Arctix men's snow pants are much cheaper and top rated on Amazon.
I've decided to order the Arctix snow pants from Amazon because they are significantly cheaper than the North Face pants. If I don't like the Arctix I can return them and then get the North Face.
I received the Arctix. I have a 38-inch waist, which is at the high end of the Large size, so I decided to order an XL. The XL is a bit too large at the waist and requires a belt, but it fits perfect over clothes over my hips and legs so I think this probably still the right size for me.
I took a walk yesterday, the temp was in the high 20s, and my legs were comfortably warm. My movement is not restricted at all although I feel more weight around my legs which might actually result in a bit more strenuous work out. Right now I am happy with this purchase.