"We had a full squad to select from, which was nice," Gatland said. It has created the right sort of headache - how to best combine form and experience.
Gatland said the toughest decisions were in the back three. North, whom he described as one of the "outstanding players in the tournament", and Halfpenny demanded inclusion on form and Gatland wanted to find room for the irrepressible Williams.
These are heady days for Wales, as Gatland readily admits. There have been times in the not-so-distant past when he has had a couple of injuries and wondered how he was going to fill the holes. Now he is wondering how to fit all the talent he has at his disposal into 22 jerseys.
"It's a great position to be in, when you're having to make hard calls about who you leave out."
While Wales have been willing to throw their youngsters in at the deep end, there is no mystery to the Irish side. They are a vastly experienced unit and maybe, just maybe, that has given Wales a bit of an edge.
"Both sets of teams and coaches know each other very well," Gatland said.
"Perhaps some of the Irish players know a little bit less about some of the youngsters, they wouldn't have played against them quite as often as some of our players have seen the Irish perform."
Wales v Ireland: Wellington, 6pm, Saturday.
Referee: Craig Joubert (South Africa)
WALES
Leigh Halfpenny
George North
Jonathan Davies
Jamie Roberts
Shane Williams
Rhys Priestland
Mike Phillips
Toby Faletau
Sam Warburton (c)
Dan Lydiate
Alun Wyn Jones
Luke Charteris
Adam Jones
Huw Bennett
Gethin Jenkins
IRELAND
Rob Kearney
Tommy Bowe
Brian O'Driscoll (c)
Gordon D'Arcy
Keith Earls
Ronan O'Gara
Conor Murray
Jamie Heaslip
Sean O'Brien
Stephen Ferris
Paul O'Connell
D. O'Callaghan
Mike Ross
Cian Healy
Reserves:
Wales: Lloyd Burns, Paul James, Bradley Davies, Ryan Jones, Lloyd Williams, James Hook, Scott Williams.
Ireland: TBA, Tom Court, Donnacha Ryan, Denis Leamy, Eoin Reddan, Jonathan Sexton, Andrew Trimble.
