I just finished Flying Changes and really liked it!
Sorry but that was, for me, the stupidest book with the most unlikeable characters, and the sequel was even worse. Yeah, moody teen gets on horse she's never seen, a middle level eventers, and has an instant rapport and does Grand Prix movements on it. Riiiiiight. The she screws up an 3-day, and within weeks wins a Grand Prix jumper class. Uh=huh. Fantasy is fine, but really.....
Any Dick Francis books - (the earlier ones are my favorites).
I've been able to pick up lots of his books for super cheap (in hardback) when they go in the sale bin at the book store. I would say they are good beach reads as I know I've read each one I own but couldn't tell you a thing about any of them :\.