If you're not accustomed to riding double-decker buses, I would recommend a ride in one as part of your trip to Dublin. There is the novelty of perspective, of course, sitting on the upper deck. But it's the gauntlet of narrow streets and bridges, combined with the unflinching tenacity of the drivers, that makes it a spectacle that never ceases to impress me.
On a related note, on at least three different occasions the Dublin City bus driver remembered me out of hundreds of riders, knew where I was going, and made sure I got off at the appropriate stop. One of those times he used the PA system which was sort of embarrassing, but still, kudos that he took enough professional interest in his riders.
And on another related note, Dublin has a bus dedicated to IKEA. If you've never imagined schlepping a deconstructed 50 pound filing cabinet on public transportation, add it to your Dublin agenda.