My husband is a big tipper, so I have learned from him. It does add up but I see how people respond to it and I wouldn't give it up, assuming the person has done his job and particularly if they do it well

You are spreading positive energy when you tip people, IMO. Of course, generous tips are not in everyone's budgets, but a smile or a "thank you" can be a tip in and of itself for a lot of CMs
I tip our driver $20 each way if we fly in and have a car service.
If we drive to WDW I tip valet about $20 for baggage handling and parking car when we first arrive. I hate the confusion of this, though, b/c I'd rather pay just once for my luggage usually one person seems to unload and another delivers them...
I tip bell services $10-$20 when bags are delivered, depending on how many bags. Like a previous poster, about $2 per bag but I round up.
I tip anyone who brings me anything to the room: room service (they say it's included but I never feel comfortable not giving at least $5), Disney Florist, dry cleaning, extra towels, etc. just a couple of dollars...
I tip housekeeping $3-$5 in the a.m. and $3-$5 at night when we get turndown service.
I tip the valet any time I get the car or drop it back off, about $2.
I also tip at the bars at the pools - just as I would at home.
And I tip the girl who does the hair wrapping! About 20%.