I've just finished reading Ted McClelland's Horseplayers: Life at the Track.
I live right near Aqueduct, though I've never made it out there, but I have been to the summer meet at Saratoga once.
The book is well done, but it betrays its origins as an edited and reworked version of newspaper columns (even though he had a book contract already while the columns were being written.) The profiles of the people he meets at the track don't go as deep as you might like: newspaper column depth rather than magazine column or book depth. The same book suffers from the same difficulty as a memoir or as participatory journalism, never digging as deep into the authors psyche as a book like Ted Conover's Newjack: Guarding Sing Sing. Of course, Newjack wasn't Conover's first rodeo as Horseplayers seems to be for McClelland. I'll be keeping an eye out for a sophmore effort.
I discovered the helpful glossary at the back only when I had finished the book, but there was still no entry there for exacta! (I used the internet to look it up.)
One more thing about reading Horseplayers: a little more knowledge about handicapping gives me a sharper appreciation for this bit from A Day at the Races: