I heard of Altamont Gardens before but it took until now that I finally got to visit - if I'd live closer I would be a very regular visitor now!
It is a huge park where you can spend hours if you like with lots of different flowers, trees, plants - most of them with name plate. I had my camera with me so took my time, but even without or with your kids running around it's well worth a visit (and any detour) I think.
It has formal gardens (not ususally my taste, but these were still nice to look at), with a rather derelict old house, a huge informal park inclusive a smal temple, river walk and a sea full of water lilies. And there's also a walled garden, parts of it rather organised and other parts just full of flowers in all colours side by side.
There's a lovely little cafe in the walled gardens - as I don't find much information about it I don't start an own business entry for that.
I had a savoury scone (buttermilk and soda) with local cheese and beetrot chutney and a large cappuccino - for € 6.40. Apart from it being very tasty I loved the cafe for being in the middle of a garden with little bits and pieces selected to make it feel like home.
There is also a hen family running around in the walled garden / cafe which makes it even nicer to sit there and relax.
It belongs to OPW which means it has the added advantage of free entrance. And they have a nursery / shop so you can buy flowers and trees for your own garden. read more