Robert Maguire’s cover is PG in what’s actually shown but I think it’s R in its execution.
Seabury Quinn supposedly wrote nude scenes into his Weird Tales stories because he knew they’d get the cover spot. In this case, illustrated by Margaret Brundage.
Another Earl Bergey lingerie cover (see also here).
And finally this one. Like Nikki, nothing obvious but the pose, the breasts pushing through the shirt, the reference to “pure lust” — they make me think this is much sexier than it probably was.
All rights to images remain with current holders.
The text on that last one makes me think of The Curious Sofa, by Ogdred Weary, erm, Edward Gorey.
I haven’t read that one but I’ve read a lot of Gorey and I can just imagine.