Remember, "niche" radio is a relatively recent phenomenon, so the musical memories of older folks are likely to be much more similar across ethnic lines than ours are today--especially if they come from outside the big urban centers. When I was a kid, we only got 2 radio stations, and they played everything: folk, country, big-band, you name it.

But I agree that varying your repertoire is a good thing generally: you could try some gospel, swing and jazz standards. And I heartily support asking for requests: you never know what songs people keep in their heads and hearts. I play most years with a pick-up band at a local church which prepares Christmas dinner for the homeless, elderly, lonely, etc. Last year a middle-aged African-American man asked for "When Irish Eyes Are Smiling": luckily I knew the words, and we were able to oblige--but who'd have anticipated it?