Whatever you get try it on with whatever you're going to wear under it.
I wear a jacket liner under mine.
Bought a HD suit over 10 years ago. Wore in Sept/Oct 2011 through multiple days and stayed very dry and comfortable and again in the rain/snow in May 2012. Rain pants have double zipper and velcro on outside of pants. The double zipper allows you to unzip bottom of pants up to upper thigh which allows you to slide your boots through the zippered opening and quickly zipper back down. Very important feature! Make sure they are loose fitting to keep comfortable. I don't use the elastic strap that fits under the boot. (I can put my rain suit on in just a couple of minutes.)
The neck of the jacket should wrap up over your neck under the chin to prevent water coming off the helmet from going down your neck.
Yellow lensed shooting goggles make it easier to see in the rain.
I have ECCO boots that are waterproof and wear the ugly thick wool socks when it is below freezing to keep my feet warm. (Real wool will keep you warm even when it is wet, not that I got wet.)
Rinse off road spray in the shower with the suit on and towel dry.
