The bike that I ride that turns the most heads and gets the most comments is definitely the Motorola Merckx. I suspect people think something along the lines of "that fat bastard sure has a nice bike." I usually am riding the Koga-Miyata or the Marnati, and since no one knows what those are, they generally ignore me. I imagine others reacting the way I reacted to people like me when I was young...a mixture of snobbery and jealousy. I used to LOVE blowing by the dude that was out of shape with his fancy bike on my Shimano 105 Sirrus. I like when folks stare at my bikes and chat with me about them, but I'd rather be back to the level where they were talking about how strong I am riding. I think the bike that best reflects my personality is the Koga-Miyata - reliable, practical and heavy.
I just love looking at rare, interesting bikes and I love watching them on the street. Usually I try to talk to folks with interesting things and have had some great conversations that way. Generally my thought pattern is: wow, what a cool person who shares my common interest. I'm definitely more interested in chatting with folks who have more odd ball stuff and I've found they typically know more about their bikes and riding. A lot of it depends on the build, the person riding it and how they're riding it. I really dig seeing updated classics, and my general approach to those people is - wow...they appreciate good steel and quality, but they actually ride and want it to work well.