Hi Mike, I called that type of job, my practice period.
1-Volume, they are there to talk to each other, so your volume should be just below their conversation. Very important!!
2-Will there be speakers? Do they have anything scheduled beside yourself? Because this type of job is laid back, and normally you are not the main theme, your playing time can be as you feel it. Always study the crowd---you will brief moments of attention, hold on to them.
The lenth of my jobs have always been three hours. I have played the first 1 1/2 hours non-stop. Once I played for 2 1/2 hours non-stop. My choice.
I do enjoy playing my keyboard, especially when there is no pressure--weddings, dance parties, ect. At the end of a three hour I am tired. When I play background music, I do not get tired. I can play whatever I want to play, stop in the middle, adjust what I want, and most of all, enjoy my playing.
So Mike, if the people are responding, play. If you are tired stop. I find it more rewarding to play than to take a break. Normall my breaks are very short.
After having said all of that, the bottom line is have no plan, go in and feel the crowd!!! This is what seperates the fair muscian from the good one. Enjoy what you are doing, they will feel it.
No set rules, just let it happen. Bring enough music to last for 3 hours, why not. If you need it it's there. If not, take it home.
Wow, I got carried away, it's 2:30 AM, gotta go. John C.