Sinaia is a Prahova-valley resort town built around the royal Peleș estate, with a 17th-century monastery and a cable car climbing into the Bucegi mountains.
Late September through October for the beech colour, but avoid the first month of November if you want to see inside Peleș — it closes for conservation then.
Look for tochitură (a pork stew served with polenta and a fried egg) or bulz — polenta baked with cheese and bacon — at the restaurants along the main street; it is mountain food, and it suits the weather.
Near the monastery end of town, which puts you between the castles and the cable car rather than at the station end.
Peleș is closed on Mondays and Tuesdays and sells timed tickets with a daily cap, so book on the official site before you travel rather than turning up and hoping.
Read more in Sinaia Travel Guide: Peleș, Pelișor & the Bucegi Foothills.