Good to hear that. The Shenandoah NP is within about two hours of me, and they boast about 180 miles of trails. I was mostly concerned about the elevation. My dad's place in AZ is at about 7,000', so I've never worried about it when using his horses.
The biggest headache about riding out here is all the regulation. In the Shenandoah they even have a rule that if you can see your horse's hoof prints you have to stay only on graveled trails. Hoof prints? Sheesh! Heaven forbid your horse leave droppings on the trail! Somebody might step in it! And forget horse camping in the park. The brochure says overnight camping with a horse is allowed, but discouraged. Huh? So you tell the warden...I mean ranger, you want to camp and he says what? "Well, I'd rather you wouldn't"? So they put regulations on it that make horse camping almost too difficult to be any fun at all. Give me the USFS and BLM lands out west every time.