I like just two layers.. Down to 25 or 30 degrees F.
Top: Fleece sweater + cycling slicker.
Bottom: Ordinary, jeans. Wet: Rain pants over jeans. I've also experimented with rain pants over tights, and so far, it is WARM.
Whenever it isn't raining, I'm often hot and end up unzipping the jacket. But, if it gets chilly, I'll zip up, and the fleece is generally warm enough.