I didn't know about the double vouchers, but I do now!
I thought the exact same thing about the origin of the macadamias and one thing I really like about the Hilton gifts is the local selections.
I don't rent a car in CNS anymore (since Uber and now Muve came on board), so the parking is not an issue for me, but DT is abut $5 cheaper each way to the airport, so the difference between the two is roughly about $40 for me. I hope DT can lose that "tour group" feel. It's possibly now the only thing I really dislike about the place, but I did notice on my last stay that despite the place being busy (APEC) it wasn't so pronounced as previous stays.