No problem 
Do have a serious think about where you're going to go, as both islands in three weeks could be a challenge, and you can end up with a lot of driving which is never as restful as you think... You never seem to be able to cover as much ground as you expect!
A few more things to mull over:
The South, as stunning as it is, might have iffy weather, particularly if you plan on going as far as Otago, which will be like Scotland in the summer. You take your chances! Having said that I'd love to go back to Fox and Franz Josef Glaciers. I don't know the upper part of the SI at all but everyone seems to love Nelson/Marlborough, and Kaikoura is a place I'd like to go to. You could spend a week in those places and save the rest till next time...?
The Far North could be a place to start off. You could pootle around there for five days or a week, then head south. Possible the right pace of life to get over the jet lag, and the Winterless North might get you in the holiday mood..
Then head south, via Taupo - the Huka Falls are magnificent, and the Huka Jet Boat ride is great. You don't have head down to the Shotover to tick that box!

Do have a serious think about where you're going to go, as both islands in three weeks could be a challenge, and you can end up with a lot of driving which is never as restful as you think... You never seem to be able to cover as much ground as you expect!
A few more things to mull over:
The South, as stunning as it is, might have iffy weather, particularly if you plan on going as far as Otago, which will be like Scotland in the summer. You take your chances! Having said that I'd love to go back to Fox and Franz Josef Glaciers. I don't know the upper part of the SI at all but everyone seems to love Nelson/Marlborough, and Kaikoura is a place I'd like to go to. You could spend a week in those places and save the rest till next time...?
The Far North could be a place to start off. You could pootle around there for five days or a week, then head south. Possible the right pace of life to get over the jet lag, and the Winterless North might get you in the holiday mood..
Then head south, via Taupo - the Huka Falls are magnificent, and the Huka Jet Boat ride is great. You don't have head down to the Shotover to tick that box!