Going to Dublin in summer? - stay at Trinity College. Trinity college is a haven of peace in the midst of frantic Dublin. Its within staggering distance of the Temple Bar district and other major attractions and walking distance from bus and train stations.

The Accommodation was a bit sparse - being empty student rooms it lacked homely touches but that was the only problem.
Rooms cost from £34 pp. and include continental breakfast. Breakfast is cafeteria style with a good choice and plenty of it. For details see www.tcd.ie/ under accommodation.
Each block of rooms has its own sitting room/kitchen where you can make tea etc and snacks but you have to bring or buy your own. I think it was possible to use the sports facilities too but it would be best to ask about this.
The greatest attraction, however, is having such peaceful surroundings right in the very heart of Dublin.

PS. If you want to take a tour I recommend Wild Wicklow tours, not only is it a very good tour totally full of blarney but Dennis also plies you with peppermints and Irish whiskey as you travel. See www.arantours.ie/