Agree about the Westin's location being best for sightseeing. It's just a few blocks from Trinity College (Book of Kells) and Temple Bar. Less than 10 minutes walk to Grafton Street, and catch the hop on-hop off bus a block away.
If a two or more night stay and you're not using points, book the Westin through a Virtuoso TA for Virtuoso amenities: full breakfast daily for two in-room guests; upgrade on arrival, subject to availability; afternoon tea for two once during stay; early check-in/late check-out, subject to availability.