Keep in mind that in Pubs and Restaurants, people's main reason for being there is to socialize, drink/eat and enjoy the ambiance. So, set your sound levels accordingly. In a bar for instance, play to the twenty or thirty seats right in front of you. Don't worry about the gang over at the far wall. They'll let you know if they want it louder.
And tell the wee woman who wants you to turn it down "You're sitting under the speaker, missus. Sit up here with me. It's a lot quieter."