It's been hard. Many books are more about elder care or informed more by a Jungian archetypal overview of life.
I just started Growing Old in Christ edited by Stanley Hauerwas, et. al. and I think it may be just what I was looking for. The opening chapter, "The Christian Practice of Growing Old: The Witness of Scripture" by Richard B. Hays and Judith C. Hays goes beyond homilies about respect for the elders to help instruct how to ground our attitudes about aging (and the aged) in Biblical examples.
Especially poignant is their section reminding us that Jesus did not live into old age:
Jesus models for us a resolute trust in God that empowers us to act freely and bear witness to the truth, even if such witness-bearing leads to death. [...] Thus, Christians are taught by the example of Jesus that we do not have to live in a cautious mode of self-protection, clinging to our lives desperately at all costs, making an idol of our physical survival. (12)
I'm appreciative of this section that it emphasizes cultivating a Christ-like attitude towards our (aging) lives rather than merely listing a prescriptive set of actions. I'm also glad to be reminded (earlier in the chapter) that old age is often a time of unexpected abundance (what a resonant phrase!) and not merely gradual surrender.