Are you willing to drive? If so, I'd consider basing a couple nights south of Dublin at the Powerscourt Hotel. It's managed by Marriott. It has spacious rooms for far less than you pay in Dublin. You can walk to the adjacent Powerscourt Gardens, and there's a fair bit to do within a two hour drive south. We enjoyed our drive thru the town that was used for the filming of Ballykisangel. We had a delightful lunch in the quaint cafe that is part of Avcoa Weaving Company.

Here is the FT thread reviewing the hotel:

http://www.flyertalk.com/forum/marri...w-ireland.html

And my post about some of the things we did.

Shannon and Dublin are the international gateways. Check flights.google.com to see options from Charlotte to either city.