I have found many of today’s alternative bands go over well with my seniors. They have a beat and usually a pop melody. If you can sing along they like it. Some popular tunes: One Sunny Day: Citizen Cope, Cough Syrup: Young the Giant, Do You Love Me: Guster, Anna Sun: Walk The Moon, Diane Young: Vampire Weekend. Katy Perry and Pink are often popular, beware Rianna and others with obscene or suggestive lyrics. As other said, Broadway tunes and Motown go over well. I have not had a problem with people disliking music from their era as Ronald suggested, but it is always a good idea to ask.