People, especially older people, want to hear songs to which they know the melody and/or words, and which evoke memories of better times.
I do pretty much the same songs each time at nursing homes. For an hour show, you need about 20 songs. I can pick 20 from a memory bank of hundreds that fit the job. Sometimes I use different styles, change keys, change tempos, lead instruments, etc., to keep ME fresh. Keep most of it uptempo, and remember that most of the residents' heydays were in the 50's and 60's!
Hammer, start singing some. Start with a couple of singalongs, and before long you'll be singing a lot of songs. I think I would get bored doing an hour of instrumentals too.
DonM