I love Gierach and Babb also...anything and everything they write.
Howell Raines' book, Flyfishing Through a Midlife Crisis,
I'll add one, from a different perspective. Little Rivers,
by Margot Page. Yes, she's a woman, but this is skillfully written. From the forward by Nick Lyons:
Little Rivers chronicles a woman's evolution from reluctant student to passionate angler and her adoption of this traditionally male sport as her own. But it is also much more than that.
It's a lovely little book with a lot of insight about the beauty of this sport we love.