Joanne is right, certainly it is good to ask the participants, but you also want to start prepared. I make my own mixes and find variety works best. I use everything from swing music (everyone loves Glen Miller), musicals, 50’s and 60’s to current music. Many of my seniors (ages 50-70+) love Bruno Mars, Lady Gaga, Young the Giant and Eric Hutchinson. Popular premixes I have used are Dynamix’s Girls Night Out Vol. 1, and Step Back in Time. The main thing to watch with seniors is volume (keep it low) and lyrics (keep it clean).