I think your summation is right on the money, naughty. Of course, any time we generalize about folks and their 'likes' we run into problems b/c of variations in individuals. Let me ask you what you think about my beliefs on this subject.
Because traditionally society's views have forced gays, more or less, to seek sexual release with a one night stand, or a stand-up in the back, dark corner of a who knows what, the gay desire has been focused on body parts, to borrow your term. Whereas, the hetero has had the opportunity to get to know the mate and actually be in love with the individual, not so much one, or more, body parts.
Regardless of the orientation, I think under the same circumstances there is no difference in the stress/importance given to body parts.
The key to all of this, I think, is love of the mate as a person. It happens with gays, its happens with str8s. Sex is just the 'little extra' something that is made complete when built on love. Without which our animal instinct becomes the driving force. (?)
Luke