We always leave a dollar person per person for housekeeping and usually 15-20% in restaurants.
We have just come back from free dining and on one occassion (Le Cellier) we left an extra tip for the waitress because the service was so good. Our big bugbear was some of the service wasn't as good and one in the Concourse Steakhouse was downright useless but still they pick up 18%.
One other thing was the Maya Grill at the Conorado Springs, we got the bill and the total was less than what we calculated from the menu. DH raised it with the waitress as we didn't want her to lose out on the tip. She informed us that the Maya Grill although on disney Property isn't disney owned. So although on the $145 bill the tip should have been $26.1 the deal with Disney was the servers only got $3.49 per person so disney were taking $15.67 of the tip. unfortuantely we didn't have anything less than a fifty on us that night or we would have left her the difference because her service was so good.