Coming from coordinating a youth ministry, it seems that there are even fewer (good) books on seniors ministry. There are lots of Christian books for seniors about senior things like ageing and retirement, but it seems there aren't that many books on doing ministry with seniors. Like I did when I was a youth minister, this page will serve as a list of resources for seniors ministry in the hope that it may help someone else in my position later down the track.
The dates in brackets are when I wrote the review, of which you can click through to read the whole thing.
Books for Seniors
Halftime: Moving from Success to Significance (Jul 2022): A little bit autobiographical in helping people who have retired to think about how they are going to do something significant (code for something for God or the church) now that they are retired. The Bible and Jesus could have been more explicit in this book, as it did come across as a little self-helpy. This could be useful to reflect on how you might live in your second half of life.
Living in the Next Phase: developing the theology, practice and ministries of later life (Apr 2022): A short book about ageing with an encouragement to live in the Third and Fourth Age with a view to exercising Christian virtues. The back had a little bit about setting up a ministry to seniors.
Finishing Our Course with Joy: Guidance from God for Engaging with Our Aging (Feb 2022): Short book by Packer challenging the secular thinking on ageing, rest and retirement, and getting churches and senior Christians to think about how they use their gifts to bring hope to this world.