On the topic of the tip percentage, I was thinking about how some restaurants in the U.S. would print out a little chart at the bottom of your receipt indicating 3 suggested tip amounts based on your specific total. It'd start at 18% with the actual $ amount calculated for you, then go to 20%, then 25%. Now granted, it's certainly helpful to have the % with the actual $ amount printed right on your receipt, but seeing the % figures on that chart was what really made me think about what would be deemed acceptable.
From most of my travels to the U.S., I do notice the recommended tip % seems to be much higher than that in Canada, where our custom tip amount would be more or less 15% on your net total before taxes. Perhaps it's just me and my ingrained ways but 18% to 25% definitely seems high to me in comparison.