Do you intend to drive from Dublin airport to Kinsale via Kilkenny and Cashel in a day? If so, allow 5hrs for the journey, plus time for stops. After driving down from the airport, there's enough in Kilkenny to keep you busy for the rest of the day, so if you want to press on to Cashel and Kinsale, you'll have to pick + choose your sites/sights. I really like St Canice's Cathedral and round tower, plus Kilkenny Castle; these alone will take at least a couple of hours:
And you'll probably spend around 1-1.5hrs at Cashel:
I don't think you'll have time for anywhere else en-route.
Are you arriving in Dublin that morning off a transatlantic flight? If so, you might be best to replan, drive as far as Kilkenny, which is around 2-2.5hrs from the airport, spend the day in the city and overnight there.Edited: 2:17 pm, May 21, 2013
Ok, if you are coming from Dublin, I suggest you come off the motorway at Crookstown and visit the Moone High Cross, the high crosses of Castledermot and the romantic mock gothic ruins of Ducketts grove with restored wall gardens, craft shops and a café.
Listen to Harveyireland she knows her stuff, she helped us out with suggestions when we went a month ago and they were perfect.
MF23 6 cities in 8 days is way to many for my tastes, all one can do is pass through, to get a good feel at least 2 days or even better 3, just my opinion.
And to each their own! We wouldn't have changed a thing! The best way we saw the country was driving and it was an adventure every day. We were happy to spend 2 nights in Kinsale and 2 in Dublin. We got up every morning without an agenda and we really liked that. When we come back...we now where we would like to spend more time. Cheers!