The Antrim Coast is absolutely beautiful. The Giant's Causeway is interesting but I don't think worth the drive if you are going direct. The coast drive is what makes it all worthwhile. We used BelfastAttactions for a private cab tour though the city and up the coast. Put over 200 miles on the cab, and it was well worthwhile. Our driver, Girard, for informative, personable and great about showing us out of the way things that we would have easily missed on our own. A nice touch was his iPhone camera which he used at every stop - instant e-mail pictures.