Always Aroused Girl has had a discussion with one of her friends about how there are two kinds of people who sleep around -- those who do it because they're being self-destructive and damaging, and those who do it because they want to have lots of fun and get off as much as they can. You should go read it, and then chime in on the comments to help suggest words that can be used for each of the two kinds of people.
Me, I favor "slut" as a positive word (and have ever since women like Sars of Tomato Nation began attempting to reclaim it, years ago). That leaves the question of what to use for a negative; myself, I prefer "whore" as a negative. Why? I've just never liked it. It sounds ugly, it has negative connotations all over the place, it curls your mouth into an unpleasant shape when you say it -- ugh, no, I just don't like the word.
Anyway, go read the post over at AAG's site and then contribute your own suggestions!