I nearly always tip the room service waiter in cash, as I doubt they get much, if any, portion of the service charge. I also tip the breakfast staff in cash also.

Funny thing... a few years ago, I realized that pretty much the only reason I carry cash anymore is for tipping. Rarely (other than a cup of coffee of bottled water at the airport) do I use cash for purchases and usually the amounts are very small.

My experience is that wait/service staff have always REALLY appreciated the cash tips. Yes, I have been accused many times by my spouse for overtipping... waiters, hotel maid, the bellman, the car valet, caddies, skycaps, taxi drivers etc... I'm certain this stems from the fact that while growing up, MANY of my close friends and several family members were in the service industry in these exact jobs and I can't begin to tell you how important the tips are to them. Yes, the system we have in the US for this type of compensation is not optimal and should change to give these hardworkers a fair wage, but until then, I don't want to make them suffer for this system, and yes, I understand that I may be perpetuating a system that isn't ideal, but the human cost of not doing so is quite material.