I really enjoyed my Ring of Kerry Tour. The driver/tour guide was very knowledgeable about the area and irish history and kept us very entertained. Despite the sometimes rainy weather, we were able to set a lot of the sights and I would definitely recommend this tour as a great way to see one of the most famous parts of western Ireland.
I took the train from Dublin to Killarney the day before, and returned on the late train to Dublin the evening of the tour and had plenty of time. The previous day I went to the Muckross House and Traditional Farms and spent the afternoon there, and highly recommend that as well.