Are your kids boys, girls, one of each? What are their interests? Do they like beaches, castles, water parks, history? Knowing things like that will narrow down prospects.
Just got back from my trip and I have a 13 and 6 year old. It definitely depends on their interests and where you are.
My observations: *The Oceanworld Aquarium in Dingle is decidely "meh". Small and ok for what it is but nothing special. *The Dublin Zoo is outstanding. Well done them, really surprised me. *Lots of horse riding opportunities in Killarney. My 13 year old almost stabbed me in the back because I said it wouldn't fit our schedule this time around. *The grounds of Muckross House in Killarney had a bazillion families there when we were there (on a Saturday with 75 degree temps). Beautiful grounds, very wide open. *Also near Killarney is Ross Castle. The castle itself is just ok but there are lots of boating opportunities. I saw plenty of families doing that. *Near Kilkenny there is a Castlecomer Adventures (or some similarly titled deal) that looked to have a lot of kid friendly activities. *Northern county Clare near Ballyvaughan, Ailwee Caves was cool and the Birds of Prey deal right next door was reasonably interesting as well.
I'll have a full trip report in the next week or so. I got back to work and found complete turmoil with people having quit and I have a whole new set of duties to figure out... Blah.
Our 11 year old granddaughter enjoyed some attractions in Tralee, which is 18 miles from Killarney.
The Aqua Dome water park, with large water slides. The Kingdom Museum, in the Ashe Memorial Hall. It is an interactive museum. The Dingle Steam Railway, which runs from Tralee to Blennerville and back.
In Killarney the tour of Ross Castle. You can walk the grounds but the tour is very educational. A pony and trap/boat ride through the Gap of Dunloe. That is an all day trip.
It might be colder than Malta but the beach at Fanore was very busy last weekend and there hasnt been a day that I've driven past Loughrea without at least someone swimming from the long point. Maybe we are just used to the cooler weather over here. The Folk Park at Bunratty Castle is entertaining and The Viking splash tour in Dublin gets good reviews.
http://www.vikingsplash.ie/
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Two rules for Ireland, Take your time & bring a sense of humour
Ring of Kerry, Derrynane House (you can walk to the offshore islands at low tide), Skellig Center (Valentia Island) & boat ride around the islands, Staigue Fort