Even though it's quite outdated, I still really like to read my old copy of Vince Marinaro's Modern Dry Fly code every so often.
There's just something about his style of writing that really captures my imagination, unlike most other books I've read.
The fact that old Vince was pretty much a dry fly man, and his writing describes how good the legendary limestoners were back in the day, also makes it good read that I never seem to get tired of