Yes, I take George with me on hikes that I know he can do on days that aren't too warm. I've found that I need to scout them out first to make sure that he can handle them. Having had to turn back with him in the past made me wish there was a book out there that looked at trails from a dogs perspective.
Obviously, every dog is different and certain breeds are, by nature, better suited for hiking than others but, I was attempting to write a book that would describe trails in a way that one could assertain whether or not a particular hike would be appropriate for their four-legged companion and would rate them accordingly.