In the morning, I took the short train ride to Feldkirch and then the bus to Vaduz.
The bus station in Feldkirch is in front of the train station, right outside the main entrance. All of the buses are yellow but the Vaduz buses are a different shade of yellow. Buses 11 and 14 go to Vaduz for about 7.60€ each way depending on the time and you pay on the bus, cash only.
The tourist area of Vaduz is below the Vaduz Castle (Schloss Vaduz), very small, and not very interesting. There is a short pedestrian promenade with restaurants and souvenir stores. The Cathedral is near the end of the promenade.
Vaduz is in a long and narrow valley with some nice mountains on both sides.