From Barcelona "El Prat" airport by bus
The company MonBus operates a bus service from Barcelona airport to Sitges:
web site: www.monbus.cat (website in English, French, Catalan and Spanish )
Tel: (+34) 93 893 70 60
The company website shows timetables and prices. There is a surcharge for fares to and from the airport. The MonBus bus stop is at Terminal 1 (T1). There is a free airport shuttle bus for passengers arriving at Terminal 2 (T2) located under the bridge outside T2B. The distance between the two terminals is 4km and the ride takes between 10-15 minutes. The shuttle bus runs every 7 minutes, 24/7
From Barcelona "El Prat" airport by train
As you come through arrivals at T2 follow the sign to the train/renfe it is accessed by an overhead walkway from the main terminal building. Trains run approx. every half hour. If you arrive at Terminal 1 there is a free airport shuttle bus which will take you to Terminal 2, the journey takes 10-15 mins and the shuttle bus runs every 7 mins, 24/7. There are automatic machines and a ticket office at the station. If you use the machines you have the option to change the language if you need to and then select Sitges as the destination the cost is €4.10 for a single journey. You take the train from airport (there is only one platform option) one stop to El Prat Del Llobregat and get off. Then switch to the other side of the platform by going up the escalator across the foyer and down the escalator the other side there you get the Vilanova i la Geltru or Sant Vicenç de Calders train to Sitges. The total travel time from the airport is about 35 to 40 minutes.
If you plan on traveling in and out of Barcelona you should get a 'three zone T10 ticket' which would cost about €29 euro for a ten journeys ticket (return = two journeys) this is very good value as a return for one person is €8.20 euro or a single would cost €4.10
As in all popular tourist resorts around the world, well trained pickpockets are on the lookout for unwary tourists, so keep you wallets, purses and telephones out of sight, and keep your eyes on your luggage.