Torla is the ton more close to the National Park, so is the best place to get beds. You can get the daily bus to arribe to the base of the National Park (with parking( or drive your own car (less in august and easter). Alpine clima, snow all the winter and atlantic climatology. (get nice raincoat). There are some limitations inside the park, so the best is get information in the town (Torla). The best season is Autumn, but all the year have something special. Get nice shoes, so probably have to walk for some hours and the best locations inside the National Park is Ordesa Valley, Soaso's Circ and "Cola de caballo" (its a fall).