Dublin airport to Ennis?

Train.

We flew directly to Ennis from the US, returned from Dublin. Multi-city fare.

You can't fly into Ennis, it would be Shannon and then a bus from Shannon to Ennjs. It is much easier and a shorter trip to fly into Shannon and go home from there. If you have to fly into Dublin you need to get from airport to train then to Ennis which is a long trip . Bus I think is shorter but still.at least a four hour trip. If you do want to fly into Dublin and home from Shannon or the other way around be sure to book multi city trip with the airline.

Ennis is not far from Shannon Airport so you might look to see if it would easier for you to fly into Shannon and then home from Dublin. (Use the multi-city option for choosing flights.)

From Shannon, it's about a 30 minute bus ride to Ennis.

From Dublin, you have two choices:

You can take a direct bus from Dublin Airport to Ennis bus station. It runs every four hours and takes just over 3 hours. There are other buses but they take longer and include a change.

You can take the train: first you take the Dublin Express from the airport to Heuston Train Station in Dublin. Then a train to Limerick where you change to a train to Ennis. This will take over four hours total including wait times.

The Ennis train station and the Ennis bus station are basically the same place.

There are no flights between Dublin and Shannon airports.

If you fly into Dublin, my suggestion is to do it at least a day or two before you need to be in Ennis. This allows you some time to get over jet lag and not have to deal with a 3+ hour train or bus ride after a long transatlantic flight.