Hi, winter is coming up (well, not quite yet but anyway...)

I'm wondering if I should get myself a classic navy pea coat. I happen to be tall and slim and the double breast feature would flatter this (making me appear broader). It seems it's very warm for winter while being more dressy than a nylon sport coat such as The North Face. Should I go with a fashion pea coat or an authentic military surplus 30oz melton wool? What should I know about pea coats before buying one? What are the best manufacturers? Any other interesting facts about pea coats?

Thanks
Frankie