I have flipped through that book and even though it's not my current style I admire it. The men and women, regardless of their background/employment strike me as artists and individualists who don't let age constrain self expression. I think the penchant for bright colors and hectic design are partly the photographer's curatorial bias, it's not really a broad spectrum of looks. Also a lot is location, they are New Yorkers.
'Aging gracefully and with sophistication' carries to me a little bit of an undercurrent association with aging quietly/unobtrusively, or alternately with being a corporate tycoon or rich retiree (in which the markers of grace and sophistication in dress and hair are class based). I know that's probably just my head, and not what you necessarily meant Lisa, as there are many older style icons whose lane is chic simplicity and I can see the appeal of that as well.
I'm not sure what lane I'll steer for by the time I'm full on elderly if I'm lucky enough to make it there, I have been dying my hair since it started to go gray at the roots at 21.