March Tenting (Queenstown -> West Coast)

Hi all, I realize this forum is just starting out but I've decided to post my vacation questions. My wife and I are visiting New Zealand in Feb/Mar from Canada and we're looking for some memorable camping/tenting. Our current plans have us spending a week in Christchurch, doing the Heaphy track with friends and spending a few days in Nelson/Wellington. We are left with 4-5 days to explore the South island and are considering renting a car in Queenstown, driving the west coast and eventually returning to Christchurch. We'd like to find some memorable day tramping / tenting along this route and was wondering if anyone had any suggestions? We are experienced and fit backpackers but won't be bringing climbing/glacier gear this trip. Thanks, rhscdn