Just returned from a 12-day bus tour of Ireland. One word-incredible! We went all around the coast of the island on the Wild Atlantic Way.
Bmet (I think it was) has a great itinerary. Blarney Castle is very touristy plus several on our bus did not kiss the Blarney Stone because we heard what the locals do to it after hours. It was raining heavy that day so I said what the hell
The castle is very cool, though, you don't have to go up to the Stone. I waited 50 minutes in line.
Ring of Dingle is where the upcoming Star Wars was filmed.
Since you are in Waterford for 3 days, I really recommend going to a 3-400 year old pub close to there called Jack Meade's. This is the real thing. They used to have wakes in the big room upstairs. The pub and the locals are downstairs. We had a popular Irish singer named Tom Comerford perform for us upstairs but I think he just sings for the big tours. He said where our Guinness was sitting is where the "guest of honor" used to be. But they have a restaurant and also some other ruins there and playground for kids.
If you're into the pre-historic stuff, you must go to Knowth/Newgrange. Neolithic mounds from 3000BC. I think it's only 2 hours from Dublin but check to make sure.