I have visited Dublin about a dozen times and almost always stayed at The Westin due to my Starwood SPG loyalt. Stayed at The Shelbourne this trip and MUCH preferred it. Nicer location (right next to St Stephen's Green) lots of nice shops and restaurants, lovely rooms.

My only gripe was the height of the shower head in the bathroom.

Taxi to the airport is about €35 and actually I took the Aircoach from the airport to the hotel for €8.50 and it dropped me 1.5 blocks from the hotel and this was marginally slower than a taxi - I think it made one stop before mine.