Northwest had- and may still have- a program called "Phantom". I was part of it twice during the last 14 years... each time for two years. Apparently only a small number of elite flyers were invited to paricipate at any one time. We received booklets of "Phantom" coupons... a maximum of 24 a year- that we could use to "reward" NW employees for exceptional service. They then turned these coupons in for significant awards. I think it was a very good idea, and should be far more widespread. While tips might be inappropriate or demeaning, some tangible ways of expressing appreciation for outstanding service ought to be available.