Like many above, it is nearly impossible for me to speak of a single favorite.anything by Mark Twain (Someone once said that if he had one wish it would be to be able "to read 'Life On the Mississippi' again for the first time." I feel that way about all of his works.)
A Reverence For Wood, by Eric Sloan
The Tracker, by Tom Brown, Jr.
Judas, My Brother, by Frank Yerby
Green Mansions, by W. H. Hudson
Now Hear This!, by Cmdr. Dan Gallery
...many others