This one is kind of subjective. For the older crowd at private parties, those ages 55 to 75 who love to dance, the Electric Slide, at least 5 polkas, Macarena, and anything by Sinatra are requested most. This is followed by Bad Leroy Brown, Mack The Knife, It's A Sin To Tell A Lie, and many of the songs of that era.
When I'm playing the barroom scene in Baltimore, where the crowds tend to be a bit younger, they seem to request late 50s to early 80s stuff, but they also request anything by Sinatra. A few that come to mind are Brown Eyed Girl, My Girl, Unchained Melody, Under The Boardwalk, and anything by Jimmy Buffett.
You can look at partial song list of mine at
www.travlineasy.com and click on the various lists.
Cheers,
Gary