12 years living in Dublin without owning a car, and I still saw nearly every corner of Ireland by train. Heuston Station handles the south and west, Connolly covers the north. The train was definitely cheaper than renting a car, and you get to nap instead of navigating roundabouts.
Full route guide: https://travel.sidewalksafari.com/ireland-by-train/
What's the furthest you've gotten by train instead of a car?

