New Zealand has an extensive hut system, so while there's lots of wide-open space one is often staying in huts. Which, at least, makes it easier getting through their biosecurity checks at immigration (if you have camping gear they want to inspect it to ensure its clean - particularly tents and stakes, if you have backpacking food they want to inspect to ensure it's all pre-packaged, etc.).
The "Great Walks", a category which includes all three of the above, require advance reservations - for the Milford I'd recommend reserving as soon as they come on-line (for next summer that happened a week ago or so).
On the Milford Track, normally the wettest of the three, I had gorgeous weather. One starts with a boat ride up Lake Te Anau:
with various sights while hiking up the Clinton River Valley:
until one reaches Lake Mintaro near the head of the valley.
From here its a climb up to MacKinnon Pass which separates the Clinton Valley:
from the more coastal Arthur River Valley:
Along the way down the Arthur Valley is Sutherland Falls, the highest waterfall in New Zealand, at 580 meters:
One continues down valley through increasingly wet forest:
until reaching Milford Sound.
On the Kepler Track...I wasn't able to complete the entire circuit because they closed the highest alpine section on account of avalanche concerns from a mid-summer snow storm (knee deep as far as it was open, apparently waist deep further on).
I did, however, get some very nice views:
before hiking down, then up the "other" side of the intended loop, to Lake Manapouri:
The Routeburn Track...I only intended to hike the eastern half, and up to Conical Hill for the views. Which were awesome:
Lake Harris:
Mt. Gifford:
From Conical Hill: the Hollyford Valley and the Tasman Sea:
Also from Conical Hill, Mt. Tutoko:
Back down...to a view of Routeburn Flats:
from Routeburn Falls:
