Catlans.
On the way to the arse end of the country, not the Gore way.
Then you come straight up to Queenstown.
Although I hear Gore has some cool things going for it, if you're into museums or something. Then you could specifically detour through on the way to... idk, somewhere.
Homer tunnel is a cunt to drive through, might be easier nicer to take a trip from Te Anau with someone else. IDK. It's worth seeing the other side, but you shit your pants when two wide vehicles (like say... campervans) need to pass each other in the tunnel.
Punakaiki is nice. Not far from Arthur's pass if you're running out of the time for Tasman (reason for it still being the only place area/district in NZ I've not been).
My fondest memories would have to be Te Anau (on the approach to Milford Sounds) and Mt. Cook national park (gett'n all up in that Hooker valley).
Tekapo is lovely. Talk to G-dizzle about that one, he goes there often I hear.