Renting a car at the Salt Lake International Airport is easy since all the majors are located right across the street from the Main Terminals. These include: Advantage, Alamo, Avis, Budget, Dollar, Enterprise, Hertz, National, & Thrifty.
Traffic in Salt Lake City is relatively light for a metropolitan area & the streets are easy to navigate since they are laid out in a grid pattern. The drive up to Park City usually takes about 35 minutes. Most of it is on Interstate 80 which is generally clear.
Utah has a great Interstate & secondary road system. Besides the advantages of having a car in Park City, you may want to explore some of the unique nearby attractions or the fabulous National Parks of southern Utah.