transportation

If you can fly into Shannon airport instead, that would be much more convenient to Ennis.

From Dublin airport, the bus would end up a little faster than a train to Ennis. The Dublin Coach company runs a bus from someplace called Red Cow near the airport. You would take a local bus (don't know the number or details) for about 20 minutes to Red Cow and then get the Dublin Coach bus to Ennis (about 3 hours). I once took this bus from Ennis to Dublin; it was ok.

For the train, you would need to get to Heuston Station in Dublin, take a train to Limerick and then change to a train to Ennis.

The Connection at Red Cow is off the Dublin Coach company bus from the Airport to Portlaoise, and is through ticketed.

Originally the Red Cow was a Restaurant, now it is a major road junction and Park and Ride location into LUAS Dublin Trams. There ar also a couple of hotels there.

https://ticketbooking.dublincoach.ie

Thanks so much for the information.