I think the prettiest actress I have ever seen was Grace Kelley. Tippi Hedren was also right up there as was Vivien Leigh and Janet Leigh.
Also Phoebe Cates and Tuesday Weld.
Hey boy, take a cold shower.
Grace Kelley would have been my favorite for the time period. She was before my time but I remember watching her in several older movies and thinking what a classy and strikingly beautiful woman she was.
Ann-Margret, as long as we are going down this road.
As far as actresses, I could probably list a bunch, but some of the more memorable are- Sophia Loren, Gina Lollobrigida, Angie Dickenson, Suzanne Pleshette, Natalie Wood, Elizabeth Taylor, and Goldie Hawn.