We rented a car to go to Poblet from Barcelona, it took us about 1.5 hours to get there. The monastery's sharp, edgy towers make a pretty sight from a distance. We were there early (at 10 a.m., when it opens to the public), not many other cars in the huge car park next door.
The entrance fee of 5 EUR includes a guided tour. They are only given in Spanish, Catalan, and French - but we were provided with a booklet in Dutch and could tag along with a Spanish group. The friendly guide made sure that we got the main message of each part of the tour.
The tour was a bit too hurried to our taste: we would have liked to stay in the various rooms a bit longer.