Actually if you want a bit of excitement then Queenstown is the place (provided you survive the approach
)
Bungie jump, skiing, hanggliding, parasailing, base jumping, aerobatics, luging....
you name it it's probably there....and if stunning scenery is your thing then there's enough here for even the most seasoned traveller. If you're in the area then don't miss Wanaka Aerodrome, location of the Warbirds Over Wanaka airshow...take a peek in a few hangars around there...you'll find Polikapovs, Harvards, Mustangs, Kittyhawks, Lavochkin, Albatross, plus a few other types.
If volcanic activity is more you scene then don't miss Rotorua (Rotovegas to the locals), more boiling mud and geysers than you can shake your fist at. Take a helicopter ride out to White Island if you're keen on strolling round a (very) active volcano...spectacular.
Oh...just read your inital post...Queenstown is in the SOUTH Island, but Rotovega is in the North and well worth the visit!