We did a Rick Steves tour of Ireland (which we loved). You can duplicate a lot of what he does by looking at the itinerary on his website and getting hints from his book. Some things that aren't on the usual tourist itinerary:
1) skip the touristy Ring of Kerry and do the Dingle Peninsula instead
2) Do homework about places to eat beforehand. Irish cuisine underwent a renaissance during the Celtic Tiger era b/c many Irish chefs returned from abroad to open really great restaurants. There is excellent food to be had, especially in Kinsale and Dublin.
3) We loved the Kissane Sheep Ranch (Co. Kerry)
4) Go to N. Ireland (Derry, Belfast) to learn about "The Troubles" and its aftermath.
I did a web scrapbook after the tour <https://sites.google.com/site/eire0912/>
The links between Flickr slideshows and google sites broke, but you can still see photos by clicking on thumbnails and links that say "see in Flickr"