Agree with all thats been said already - You will have such a lovely time there on your holiday, its a place I know very, very well!! Nice sized town, easy to navigate around, cobbled streets etc, called a city for historical reasons only, very easy to walk around. Kilkenny has lots of medieval historical buildings and the town still retains that lovely charachter.
Lots of nice coffee shops and small boutique shops, you have to visit the Medieval Castle and do the tour, connections to Queen Elizabeth 1 etc, and spend time walking around the beautiful grounds, make sure and find out the duck pond! Your little children will love feeding the ducks and swans! There's also a really wonderful (newish)kiddies playground in the park, ideal for your children! If you like historical buildings, then you should also visit the Church of Ireland St Canices Cathedral and Round Tower, which is a magnificent building dating from the 6th century. Some great night life/pub scene also, but nicer mid week, than at weekends when unfortunately the centre can become a magnet for hen and stag parties, Lots of great places to eat out in also. Langtons Hotel (John St) is a good place to bring a family for lunch/dinner as they do an excellent good quality childrens menu, and you'll get generous portions also! Try and have a pint in Tynans bar which is located beside the river in the city centre across the road from the River Court Hotel, its a lovely traditional Irish pub, and they do traditional irish music sessions also mid week, if that your kind of thing!
Wallslough village itself is only a couple of miles from Kilkenny, its a gorgeous place to stay. Rural and should be quiet, a good place for little ones! You should also visit the craft villlages of Benentsbridge (look out for the "Moth to a Flame" candle shop on the outskirts of the village, on left hand side, lovely place for gifts!) and also the Nicholas Mosse pottery centre plus delicious coffee shop - they have a "seconds" shop there also where you could pick up some beautiful pottery a reduced prices.
Also drive further south to Thomastown and the gorgeous village of Inistioge (pronounced Innis teeg) gorgeous riverside location, stunning scenery, some good local pubs, and if the sun is shining bring a picnic! I do hope you have a great time and if you need any specific information, just PM me and I'd be more than happy to oblige! 