Queenstown Airport: The sensible car-free arrival is a direct Ritchies coach to Wānaka, via the Crown Range: about 1 hr 10 min and roughly NZ$46 one way on current quoted fares. Book the departure that matches your flight; it is far better value than a private airport transfer. A hire car is the better choice only if you will use it for trailheads, ski fields or Mount Aspiring National Park.
Wānaka bus stop, Log Cabin, 100 Ardmore Street: Intercity and Queenstown coaches use the lakefront Log Cabin stop, opposite the i-SITE. This is effectively central Wānaka: most lakefront accommodation, cafés and shops are a 5–15 minute walk away. Do not pay for a taxi before checking your map.
Wānaka Airport: WKA is primarily for scenic and charter flights, not a useful scheduled-airline gateway. Arrange a rental-car pickup or taxi in advance for the short trip into town; there is no airport rail or dependable public-transport transfer to rely on.