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).
Joanne hit it dead on with surveying your group. Our “older” generation is now from the 40’s and 50’s but, I’ve noticed that many have continued to grow their music listening tastes along the way. We usually get real into music in our pe-teen and teen years moving their music influence into the 50’s and 60’s. The birth of rock! Everything from Elvis Presley and Buddy Holly, to Jimi Hendrix and The Beatles. Put on some Little Richard and just try to keep from moving, I dare ya.
I agree with Stephen, Janet and Joanne! I had to chuckle to myself, because your question asks about teaching older adults “light” cardio and resistance. So, I think that Elvis, or Little Richard just might get them a bit too revved up (only joking)!
Definitely canvass your group (I do it via a written poll or suggestion questionnaire where you limit their choices to music that you currently have or have access to so that you’re not having to chase all over looking for specific sound tracks etc).
Good luck and have fun with your new class/group!