Olivia Newton-John captured wholesome girl next door beauty like nobody else in the world.  An obvious choice to play Sandy in "Grease" her Australian accent, good looks, and impossibly perfect smile made her one of the more endearing ladies of the 70s.  Taking a cue from her wild turn at the end of Grease, she tried to toughen up her image by becoming the Ultimate Aerobic Bad-Girl when she recorded "Physical", but it's her gentle outdoorsy quality that I enjoyed the best, and primarily represented in the gallery below.  Though there is certainly something to be said for her neon purple Xanadu phase as well.