As beautiful as this vista is, most of today"s visitors to Park City are there to spend the day inside. Sundance Film Festival, the nation"s biggest celebration of independent cinema, opens today and runs through January 29. The careers of Hollywood directors such as Quentin Tarantino and Steven Soderbergh were launched here, and every year a new crop of greenhorns arrives in this mountain enclave with the dream that they"ll leave with a distribution deal.