Yes, always. I figure that the tip is part of the spending budget when I dine out or use a bellhop or valet parking service.
While dining, I always figure on a 20% tip to begin with. If the service is not all that great, it drops to 18% and if it lacking, it drops to 15%. There was only one time that I did not tip. Well, that is not true, I did tip, one cent that one time. The waitress made a mistake on our order and refused to admit she made a mistake. I am allergic to clams, so I would never order linguini with clam sauce...not even by mistake. I ordered linguini with Alfredo sauce.