For the trip to the glowworm cave in Te Anau, I actually like the ancient limestone cave itself even more than the glowworms. I hoped I could come closer to them.
I want to go to Milford Sound again after reading your comments! Added trekking to my to-do list‼
I would suggest you to try Doubtful Sound instead Milford Sound again . It will be another place you could add on your diary .