depends on the author, depends on the sex scene. Scenes where it moves the plot or the relationship forward, yes (but not in anatomically-correct detail, please). There just because? I'll probably skip over it.
On the other hand, I like the sex in the In Death books, because even though ti doesn't move the relationship forward any (well, hell, they're married - how much more forward do you want to go?), it usually is for an emotional arc, and the emotional arc is really what those books are about (well, that and the mysteries are pretty good too.)