A comment from my last post:
Do Asian guys normally have smaller cocks?
As it happens, I'd like to answer that question.
Unsurprisingly, however, I have more to say about it than that. First, let me start off by pointing you to this map. I can't really vouch for the underlying research, but I will say that it comports with my experience, which could be summed up with a vast (but not, I hope, offensive) oversimplification: black cocks are bigger than brown cocks; brown cocks are bigger than white cocks; white cocks are bigger than yellow cocks.
As I said, that's an oversimplification. There are hung guys from the far east, and there are small-dicked Africans, though I can only remember playing with one black guy whose cock I would actually consider small. But, on the whole, some ethnicities/nationalities have bigger cocks than others. There are plenty of guys who will tell you that this isn't the case, but I don't believe them. (Typically, the guys who tell me that are guys who have not personally examined as large a sample size as I have; they're also usually white guys who mostly stick to white cock. More for me.)
The bigger question here is whether size matters. And the answer is yes, but only to some people, and in varying amounts. There are, of course, the hardcore size queens, for whom bigger is always better, and who will often end up with people that have you asking, "What does he see in him?" until you see him in a Speedo. There are also the (significantly rarer, I believe) guys for whom a small cock is a prerequisite to lust.
Most people have some sort of preference for larger or smaller cocks, but it's just not that big of a deal. Here's an analogy. Let's say that your favorite ice cream flavor is rocky road. If you go to an ice cream parlor, you're going to order rocky road. You might be disappointed if there's no rocky road and you have to get something else, but you'll take something else. But let's say you're in your office, and someone comes around and offers you a cup of strawberry ice cream. Are you disappointed because it's not rocky road? Hell no: you got ice cream! This is how most guys are with penis size.
When you're talking about body parts and attraction, you (or at least I) have two different things going on. There's your aesthetic attraction and then there's your visceral attraction. Aesthetic attraction is something that you look at and think, "Oh, cute!" (or whatever). Visceral attraction is something that gives you wood. I, for example, still have an aesthetic appreciation for a good pair on a woman, but it's a purely mental phenomenon. A great set of manboobs (which in my case mostly means fabulous nipples), on the other hand, makes the motor run. You can plot your levels of aesthetic and visceral attraction on a graph. I have done so: [I apologize for the orientation and crappy quality of this graph. I sketched it on scrap paper and photographed it with my iPhone. I'll fix it later and remove this note.]
I have, as you can see, more of an aesthetic than a visceral appreciation for cock. Obviously, I have some sort of visceral attraction to them since I like to make them shoot, but I get a lot more worked up (aesthetically and viscerally) by lips and nips. And when it comes to size, well, it varies. By and large, I like my men's cocks to fit the stereotypes and the body. If I'm playing with a Black guy, I like a big cock, especially if he's a big guy. If I'm playing with an Asian, small and uncut, please. I'm sort of ambivalent on cock size when it comes to Latin men, and on white guys, it's mostly a question of how tall the guy is. I find a long, well-formed cock to be very pleasing (aesthetically much more than viscerally) on a tall white guy. Then again, regardless of race, there's something very entertaining about a short guy with a massive dick. It's just cool.
But none of these things matter very much. They're just nice to see in that I'm-at-the-ice-cream-store-and-I-can-have-any-flavor-I-want-plus-sprinkles-and-a-cherry sort of way. (When I'm dealing with a guy one-on-one, I'm more likely to just focus on whichever feature I like best on that guy.)
And, again, that's just me. There are plenty of guys for whom big dick is the main attraction. But big dick can mean a lot of things. I, for example, do not think of myself as hung, but if you look at the statistics, the circumference of my cock is in the upper levels, even while the length is just maybe slightly above average. So I not infrequently have the experience of hooking up with a guy who's slightly aesthetically disappointed by the length but is viscerally ecstatic when I get around to fucking him and who leaves thinking that I'm huge. I'm really not boasting here: my cock is what it is, and everyone who likes to have a lot of sex with multiple partners makes the most of whatever advantages he has. I happen to think that my technique is more impressive than my shaft, but whatever brings guys I want to play with to my bed is fine with me.