Halle Berry and Catherine Zeta-Jones get nods for gorgeous perfection, but sex appeal is more than looks.
My vote would go to the aforementioned (post below) Charlize Theron.
Some proof:

Great cheekbones.

Great body- not too much fat nor oversized breasts.
Plus, she's willing to get nude and frisky (lucky James Spader):
Charlize Theron - Hot Scenes from '2 Days In The Valley' - The funniest bloopers are right here
And:
Charlize Theron Pool Scene - More free videos are here
Who else could top this list?