Misha, your description of writing effective love/sex scenes is great! I agree that sometimes authors seem too, uh, eager to get to the sex, whereas a little more build-up would make the scene better. And I agree that there is nothing wrong with closing the bedroom door, although that can make it a little harder to convey how the moment has changed the relationship or revealed something about the characters. I agree that awkwardness can be human and endearing.
As I was writing that I was thinking about humor and how I’m not as sure about humor in the bedroom; I remember reading a scene where the author was trying too hard to make her snappy-patter characters continue that in the bedroom, and it ended up not being funny, sexy, OR emotionally engaging. It was just cringes all around, but that wasn’t what the author intended.
Jenny Crusie has a sex scene in FAKING IT where the heroine loses interest partway through and it is laugh-out-loud funny but that’s fine because it’s not also supposed to be sexy and emotionally engaging. It is supposed to make you feel disengaged from the sex, the way the heroine feels. It turns out that only when the heroine is honest about who she is can she, uh, have a happy time, and so the ultimate sex scene is rewarding because she has, by that time, admitted the truth about who she is. I thought this was a fantastic use of sex as a metaphor for emotional freedom as well as an actual physical act.