I'm going back for second trip this March. Went 5 years ago and rented a car. Besides almost getting hit by a bus at the roundabout leaving Shannon airport, it was pretty easy driving. Stayed a few nights in Killarney, 2 in Dublin and 3 in Galway. This trip we are staying only in Galway before heading to Scotland. As big as Ireland seems on a map it's really not that difficult to transverse across by car in a few hours. Just have to get lucky with the Cliffs of Moher, we got up there on a postcard perfect day in Galway (55 and sunny) and it was complete fog up there. Went to Aran Islands instead which was a fun and easy boat ride from near Galway.
Dingle/Ring of Kerry is very long. We stayed in Killarney and drove out to Dingle past Inch beach. Very fun drive and not terrible far. Cork was like Philly, Dublin was ok, but the charm of Ireland is in the smaller towns and Galway is like the Nashville of Ireland.