What day trip should my wife and I take from Dublin?

My wife and I are visiting Ireland!! Unfortunately, we will only have 3 days in Dublin before we fly out to the UK. We are in our late 30's and enjoy hiking, travel, pubs and music, and I'm very interested in archeological and historical sites. We want to see the beauty of Ireland outside of Dublin, but we will only have one day to do it. Please give us suggestions on how to make our one day out of Dublin the best day trip we can possibly take. Open to all suggestions! Thanks in advance!