Thanks for reaching out on our Community!
I think that your most convenient course of action is indeed going to be to catch the Dublin Express
bus from the airport directly to Temple Bar
. The stop you'll need to get off at is Wellington Quay, stop 312 (whether for the general Temple Bar area and the Hard Rock Hotel). The journey takes about 35 minutes, and the bus stop is really right next to Temple Bar.
Alternatively, you can also look at the Aircoach Shuttle
and get off at O'Connell Bridge. You'll have to add on a 10-minute walk from the bus stop to Temple Bar, however.
You'll find timetables and booking options on both the Dublin Express and Aircoach Shuttle websites, but you can also take a look at Transport for Ireland
and Rome2Rio to get a further idea of timetables.
Let me know if you have any other questions or need any help with your upcoming visit!