In a relationship do men usually feel more ...

Men definitly feel more connected PHYSICALLY. Emotional and mental connections, along with intimacy, only come as a result of sexual encounters with their partners. The rest is a moot point.

Only on rare occasion do men develope an emotional attachment to some one they have never had sex with.

Annette is right. For us, all those other connections start with the physical. For us, sex is the primary way we give and receive love. It means more to us than women understand.

Very interesting question. I have never read any specific research nor asked this question to any male friends, but as I would say that the emotional connection is the most enduring

It depends on the person, but for the most part, a man can have sex and never become emotionally involved with that person.  Sex is a physical act for them. (same thing for some promiscuous ladies, too).  But women tend to get emotionally involved with a man who gives them good sex.  We romanticize it.  During my 25 years of being divorced and dating a lot of men, I always had long term relationships of 1 to 8 years. Several never seemed to be "emotionally involved" but they stayed around. I just did not think they "really loved me" in the sense that they would have married me if the subject came up.  Several whom I broke up with, went right on with their lives (when I thought they would be heart-broken and begging me to take them back!)  But they didn't.  So who knows. I say we women commit more strongly on every level.  But that's just my opinion. 

Not all men. Some of us need the whole package. Sex without feelings just leaves us lonelier than we were in the first place. I know I can't be the only man that feels that way.