We visited Kilkenny a few years ago, also because of Rick Steves books. I think it is overly hyped as a medieval site; compared to someplace like York, it is pretty minimal. You might stop there for a couple of hours if you were in the vicinity. Ireland's scenery is spectacular on the west side of the island. You could drive from Dublin to Galway in a few hours. (Check theaa.com or theaa.co.uk for mileage estimates.) While Ireland's roads are slow, keep in mind that the entire island is about the size of Ohio. If you wish to stay near Dublin, Glendalough is lovely. New Grange is also supposed to be interesting, although we haven't visited it yet. From Galway, you can visit Connemara, the Aran Islands, or you could dip down into County Clare for the Burren and a few ruined abbeys. Check out irelandexpert.com for good information. Hope this helps.