I usually tip 20%, more for exceptional service. Even if the service is somewhat lacking, I tip in the 18 - 20% range. The only time I've felt guilty about tipping was last week, and I shouldn't feel guilty at all. A friend and I were out to lunch, and our waitress was also waiting on a table of people that she was obviously friends with. After she served our meals, she went over and talked to her friends (in between serving other tables). She never came back to ask how our meals were or if we needed something else to drink. Well, my friend did want another cup of coffee and this girl wasn't even glancing in our direction the entire time. My friend actually got up from the table and called over to her to ask for more coffee. Are you ready for this? The waitress said, "Sure", AND SAT DOWN AT THE TABLE WITH HER FRIENDS!!!!! We were speechless! I then had to chase her down for the bill and, being the idiot that I am, left her 10% AND FELT GUILTY ABOUT IT! After reading this thread, I no longer do. Thank You!