Experiences with going "self-service"

What are other people's experiences with going "self-service" during an LD? (private room, of course).

I'm asking because I'm getting tired of jettisoning my load in my jockeys, and the clubs I frequent tend to not offer extras (I know I can find other places, and there are always exceptions to the rule), but I'm thinking about going champagne and then asking/telling the girl I'm going to pull it out but take care of business myself. Do they normally freak out when you do this, and/or demand extra money?

Also, what's the deal with COT/F (cumming on tits/face)? Of course it depends on the dancer, but what kind of responses have other people who've tried this gotten, and how much do you think you should tip (if any) for allowing it?