I'm all for pre-paid tipping. If I could get away with carrying no cash at all I'd be a happy camper. On Princess we used to be able to tip with personal checks. Don't know if we can still do this (Give the waiter, steward, whatever the tip as a check made out to Princess cruises. Princess cashes it for it's employee). I also would hate it if we couldn't adjust the tips up and down. I bought pre-paid tips on my Carnival cruise last fall. It came in the form of non refundable vouchers. I ended up giving everyone the vouchers plus addtional cash because the service was excellent, but if it had been lousy I would just have been out my money, bad deal I think.