Depends a bit where you're from, and therefore what songs they might know.
A little group I played with used to do songs from the late 50s, early 60s playing for senior citizens in their 70s/80s- Buddy Holly, Elvis, Lonnie Donegan, Beach Boys, Beatles, etc, all went down well, and they knew the words better than us! But being in Scotland, we would play a few of the Scottish old standards - Westering Home, Skye Boat Song, Mairi's Wedding, etc.
And by the way: they LOVE "You are my Sunshine"!! What's wrong with it? I used to cry crocodile tears in the sad verse, and make them laugh!