Favorite town in New Zealand!!!
Queenstown is a great place to visit as there's something for everyone. There's great food, shopping, nightlife, and sight-seeing. The range of activities was incredible (bungy jumping, sky-diving, gondola rides, jet-boating, skiing, paragliding, fishing ... there was even a luge track!). It's located so a day trip to Milford Sound is easily done ... and it's definitely worth seeing. Any place in the south of the South Island is pretty accessible from here.
Insider Tip:If you're going to NZ in the "off" season (end of winter/beginning of spring), maybe wait to book some of your activities (like bungy jumping and bar crawls) til the day of or before, as there are some great last minute deals you can grab when you get there.