While I love all the parts of the female body to me its the eyes. WIth them you can see the emption and feeling, and you can use your imagination as to what they are thinking. Also, watchin gthem look at your body, or looking up at you as she is down below is one of the sexiest sights that you can see.
The only places that I have cummed was in the pussy and the mouth. the thought of seeing cum on my girls breasts and around the mouth has always been a a turnon for me though. I think it depends on the situation, and the feeling that both people have at the time
I like them when they are proportional to the body.. Sometimes really big boobs just do not look good on some people, and vice versa.