The Fiordland area!!!!
I personally lived in Queenstown for about five years before I finally jumped in the car with my now wife and drove to to Milford Sound. First town to hit is Te Anau, a tranquil little town half way between Queenstown and Milford Sound situated on a beautiful lake.
From there it is a two drive up past the lake, through the Homer Tunnel, to Milford Sound. Check out this video below of the area.
Once you are here there is plenty to do, check out www.fiordland.org.nz for all of your accommodation and activity needs
One product activity i can recommend to do is to do a Doubtful Sound Cruise. Whether it be over night or just a day cruise it is a must to do while in the area. Nothing better than getting out on the water to explore this amazing area.