I think your experience the other night actually explains one of your original questions.

I've never understood why people will sit close to the stage when they have no visible interest in the performance, especially if they'd have more room and greater privacy further away. I'm convinced there's an unconscious desire to be "near the action" -- whatever that action is -- which is something bar managers recognize. So bar managers are just trying to create some/any kind of action when they book live music.

For what it's worth: When we have a table of talkers like you had the other night, I usually try to get them talking to me. I usually ask some kind of question to them -- How's the meal? How's it sound? Anything you want to hear? Want to hear a joke?

It doesn't always work, but at least they have to acknowledge your presence...and sometimes that's enough for them to tone it down. (It's kind of like the greeter at Walmart...they don't really care that you're there, but studies prove it helps deter shoplifting because someone has said "I see you" to the potential thief.)

And, when it DOES work and you can engage them, you can turn potential headaches into a drunken chorus who are at least on your side.