I understand there is a shuttle bus from Shannon airport to Limerick train station. Then, I think there are trains scheduled fairly often from Limerick to Dublin. We plan to take this trip the first week of August. Should we buy our tickets online before we leave the US, or would it be OK to buy our tickets when we arrive at the station? I would prefer to wait until we arrive since I'm not sure exactly what time we will be getting to the airport (via group transfer from hotel) and which train, time-wise, would work the best for us. However, I'm afraid if we wait to purchase the tickets, we would be risking the train being already fully booked. Is that a valid concern?
Have to checked to see if there is a bus?? I don't know a whole lot about the train from Shannon to Dublin. I have used the bus from Shannon to Galway twice and it was great!
It is highly unlikely that the Limerick-Dublin trains will sell out. You also could take the bus all the way from Shannon to Dublin (with a change in Limerick). Travel time on the train from Limerick to Dublin is about 2hr30min. On the bus it is 3hr15min, but the fare will be cheaper.
I am sure you realize you can fly into Dublin from Portland and from Shannon to Dublin. Check to see how much of a price break you will get by buying train tickets in advance. I have no experience buying train tickets in ROI but the saving in Britain are substantial. You might have a theoretically shorter trip using the train but transferring between the bus system and train system may eat up all your perceived time savings. For the little bit of time difference you might be better off staying on the bus.
Thank you all for the great suggestions - they were a huge help! We decided to take a bus (JJ Kavanaugh's private motor coach company). There is a direct bus scheduled from Shannon airport to downtown Dublin, very near our hotel. There will be no transfers involved and the price was very reasonable. Bought the tickets online on their very easy to use website after having some questions answered very promptly by email (re:luggage). We actually are flying from Portland to Shannon with a group (my company) and they are taking us back to Shannon airport where most of the group will fly home from. We decided we wanted to stay a few more days and visit Dublin also - that's what necessitated the journey. We fly home to Portland from Dublin. We're hoping this bus company is legit and reliable!!