Well 50-60 is my favorite riding temperature! What I call fall type riding, definitely not winter clothing. I had on knee warmers, thermal arm warmers and a vest. I do have heavy duty winter riding clothing, though. Today was more like, wow, I haven't ridden in these temperatures in about 5-6 weeks. It's about 75 now.
Emily, early morning riding is extremely peaceful. I get up early anyway, and it's much preferred than trying to ride after work.