I'm 5'11" 270 and wear mtb shorts. I have Hoss Ponderosa (passable) and on the recommendation of this forum, I got a pair of Aerotech Designs "Cargo shorts" which I feel are more comfortable (although they don't have side pockets, be aware of that!)
So I wear mtb and mtb "style" padded bike shorts on my road bike. I also have Specialized white mtb platform pedals on my road bike. I'm comfortable for the most part, and the small niggling discomforts I have are not issues with the shorts.
I'm definitely in the minority on my Sunday rides, as 99% of the road bike folks are in Spandex and jerseys. I wear tennis shoes, mtb shorts, and a tee shirt. I have yet to find a reason to wear the shorts, or get a jersey. I'm comfortable, having fun, and getting exercise - which is what it's all about for me. At some point, as I get more into cycling and lose weight/get faster, I may want to wear Spandex and jerseys, but I'll buy that stuff because I want to wear it, not because I worry about what some stranger might think.