Every year, millions of Americans and their families take to the highways, traveling far and wide to summer vacation destinations. Some families tour historic sites, museums and attractions of all kinds, while other families head for the nearest beach for sun, sand and surf. Many families, however, are outdoors vacationing families, who head to a quiet spot in the wilderness to get away from it all. If your idea of the great outdoors is more extreme than most, or your definition of “roughing it” is a bit more posh, finding the right recreational vehicle can be a challenge. Here are some of the more unique RVs in existence, either for their capability or for their amenities — or both.