There's a new spa hotel just outside Cavan? Sorry can't recall the name. Only an hour from Dublin (ok hour and a half)
Also the Nuremore in Monaghan is supposed to be good.
Stayed here also and it's top-notch. The food would be better than here:http://www.farnhamestate.ie/A friend stayed in Ballymascanlon House Hotel, Dundalk, not too long ago and was very enthusiastic about it
The website of the Hillgrove Hotel, Monaghan looks nice, but I haven't stayed there. It says it's recommended in the Georgina Campbell food guide.