The Ryokan (japanese word for "traditional hotel") Hoshi is the oldest hotel in the world, since it was build in year 717! And the same family have run it all along this centuries. Placed in Hokiruki (Japan), the Hoshi Hotel looks like the perfect place to have a japanese old style vacation, including thermal baths, being one of the few places where both men and women can entered the baths together. Ok, it's 300 euros (385 US$) per night, but it's definitely a place I would like to visit before I die.
Source : Mymodernmet