Head for the animal shelter and you'll find lots of large dogs there. Most will be heading for doggy heaven since most people go for the small dogs and puppies. Yes, they may be cross breeds, but usually those are much stronger than purebreds and have better overall health and stamina. Unless you expect to race your dog downhill on ski's, whatever one you get will more than keep up with you on a hiking trip. Hey, my little terrier can out-hike me any day of the week ...