I haven't yet looked at the rail schedule yet, but I am looking at Rick's book on Ireland to get some idea of travel time between the three locations in Topic, 2009 book, pg 417.
After a few days in Dublin, I plan to see the sites around Galway, Inishmere, and Dingle, general area. The book shows 7 trips daily from Dublin to Galway, and 3 hours of travel time. From Galway to Dingle by bus, 5 trips per day and 7 hours of travel. 7 hours?! I see the distance via Google is about 160 to 180 miles, 4 hours, depending on the route. Apparently, the bus moves more slowly along the route than an automobile. Possibly the road is difficult, winding. I don't see in his book yet, whether the Irish drive on the opposite side of the road from us, USA. Comments?
I definitely want to get to Inishmore, and stay over night. I only have 4 days of time after Dublin to travel to this region. My top choices would be Inishmere and the Cliffs of Moher. Dingle is a possibility but might be a stretch for time. I'd probably want to spend more time enjoying natural sites than historic sites, and possibly do some day hiking. The Burren area has some appeal. I see the area NW of Galway about 60 miles is pretty rugged. I see it's a national park. Comments on any of these activities?