We are visiting Ireland and aren't renting a car. So we are looking for (preferably inexpensive) transportation options to Giant's Causeway from Dublin, Ireland.
You'll get transportation options at http://www.causewaycoastandglens.com/Getting-Around.T216.aspx.
You might want to check out http://paddywagontours.com/. They are Ireland's tour operator for the budget-minded. They have several day trips (and longer) from several cities in Ireland. about 5 years ago