Eye candy is great, but as with flight crews, I like to see at least one older, seasoned crew member when I am a cigar-tube pax.
I recall flying Sunjet a few times in a row between Newark and Orlando; always wound up with the same crew. The chief FA was everything a FA should be: friendly, competent, patient, but with a zero-tolerance policy towards rudeness and inefficiency, and just salty enough to keep everybody smiling. And certainly not unattractive for her age, not that that matters much to me. Definitely more functional than decorative, and her younger charges seemed to like her as much as they feared her.
In the long run, I am happiest on an airline flight if there is a Pretty Young Thing sitting next to me...