To Dublin I'll add:
The Westin - SPG, near Trinity College
The Shelbourne Renaissance - Marriott, on St. Stephen's Green
Conrad - HHonors, kinda average and overpriced
For a well-priced 4*property, large rooms, new build - 15 mins form city centre, in a pleasant enough part of the city, beside Kilmainham Gaol, I'm also happy to recommend the Hilton Kilmainham. I use it for mattress runs occasionally.
For 3* properties look at Jurys Inns.