While I'm sure Dublin is a pretty town to visit, my ideal trip to Ireland would be all around the country. Rent a car and drive to all the iconic town and places - Galway, Cork, Rock of Cashel, Cliffs of Moher, maybe Skellig islands... there are nations whose capital is not representative of the whole country, or at least so breathtakingly beautiful that it makes up for not seeing anything else, and I believe Ireland is one of those cases. Same as Norway, I'm sure Oslo is kinda pretty, but you really have to see the fjords.