Since I live in the Wasatch Front area of Utah, I recommend legendary Utah resorts such as Alta, Brighton, Canyons, Deer Valley, Park City Mountain Resort, Snowbird, Snowbasin and Solitude. These resorts certainly have altitude; many lifts top out at 10,000 feet. Here's the science, according to numerous studies: High altitude, defined as 5,000 feet above sea level, creates air that is less dense and contains less oxygen. The lower density means there is less air pressure. That's why your first day or two at altitude will leave you out of breath just from walking up a flight of stairs.