"I just noticed the bola tie is the official Arizona neckwear, so I would consider wearing a black bola to an event with the invitation of "black tie or national attire"; even if it were black tie, o'natural or national attire..."

I got some nice bolos at Sheplers. Rocky Mountain Western has a great line of bolos, too. I wear them with suits (and boots and my Stetson) and with the kilt (No western boots, of course, but the Stetson sometimes.). Some of the bolos are more dressy than others. I prefer the dressy ones.

A guy at a conference told me he wouldn't have the cajones to wear a bolo to work. My reply was "I wear mine around my neck."

I have also noticed that, since I added the kilts to the office rotation, nobody makes smart remarks about my boots-and-bolo-with-suits any more. Whatever. If you have the desire to wear a bolo, and the taste to make it fit, there is no reason to hesitate about wearing one.