Joe, I can relate to the forgoing information provided by previous posters. I played in a cabaret style band (guitar/banjo, bass, trumpet/flugel, t-sax/s-sax, keyboards/accordian, and drums). With that lineup we played dixe,swing,country,rock'n roll (no heavy metal), pop: also waltzs, polkas, sambas, tangos, tarantellas, rhumbas. What we did was get a rough idea of the "genre" of the audience and play to it. The result was we ended up with multiple set lists with many songs crossing style boundaries.Equally important is that good music incorporates: a structured intro, middle, and ending;steady, in the pocket tempos and balance. For example a younger crowd would have a heavier bass sound with faster tempos.
Equally important is that I would cruise the crowd before we started and during breaks and find out information on birthdays, anniversaries, special occaisions, out-of-town visitors, etc. Our band would then acknowledge that to the crowd during our gigs. I do the same procedure playing at seniors centers with the additional effort of getting to know the attendees names. When I play the next time I usually say something to the effect of "I see my good friend Elmer is here this afternoon-hi Elmer" I then cruise the audience during my breaks and make new friends. This socializing is an immense help in getting other gigs that pay. Hope this helps. Dennis