For a first time it's probably easier to take a package, at least that way you know your flights, accommodation, skis/sticks & lessons are all arranged and also that if there is a problem you have a rep to go to who will hopefully sort things out for you.
Be aware that that time of year is going to be VERY expensive, and extremely busy. Most resorts would have close to full occupancy over the New Year period.
As regards where to go, at that time of year the higher the better in terms of getting snow. This year was a really good one, but the previous year was atrocious in the early season. The downside of going really high is that the altitude can affect some people. A site you may find useful is [broken link removed] which gives very good information about just about everywhere you can ski.
If you're in any way near Kilternan (South Dublin / North Wicklow area) I would highly recommend you do a couple of lessons with the
Ski Club of Ireland on their artificial slopes. It will mean you don't spend your first day of your skiing holiday simply learning how to side-step up a hill, so once you get to your chosen resort you'll be able to actually move on your skis already, even though it will be on very gentle slopes at first.
By the way, unless you're all very fit, I wouldn't bother booking a hotel with lots of sporting facilities as the likelihood is that you'll be too tired after your skiing to be able to take advantage of them!