Kilmainham is near enough to the Phoenix park and is a mature area. Also very near to shops, pubs, restants, hilton hotel etc Also the Royal Hospital is on your doorstep, a very nice amenity.
Try Stoneybatter up around roads like Mount Temple or Viking. Very old area, quiet and easy commute into town. Great local pubs like Mulligans and Walshs. Can't go wrong here.