Dublin airport to city center

With 4 people and luggage, I would take a taxi straight to your hotel door for about €30. The faster buses cost €6-7 per person (maybe not for the kids, but only serve specific stops) and the city bus is too slow.

I've used the tools on the Dublin Bus website to identify bus routes and stops that I'll use to get from the airport into the city -- http://www.dublinbus.ie/

There is the #747 bus, which is the €6 fare mentioned. I'll be using the #16 bus to get from the airport to where I'm staying at Trinity College, at half that fare.

With two small children in tow do it the easy way - taxi.