There are two options for the journey - the scenic route or the motorway. The scenic route will take you along the winding roads of the coast. At points the journey is slightly hair raising as the coastal roads take you along cliff edges. If you are prone to car sickness you may want to take whatever precautions you find most effective for the journey - this drive is certainly anything but a straight one. However, it is definitely worth the extra time and effort - allowing you to get up close and personal with the craggy cliff edges and glimmering shores of the Costa Brava.
If you are short of time or are not too fond of heights, you may prefer to take the more direct route to Sitges - along the C-32. This should shorten your journey time and provide a more direct route. However, don't forget that this road will require you to pay a toll. Where as the other option will be free of charge.