I was in Gold briefly as a Qantas benefit, but didn't think much of it. At the Novotel on Collins St, Melbourne, the prority check-in line was ignored in favour or non-status people arriving after we did. We requested late check-out and were given a one-hour extension, from 11am to 12am - but the room access card expired at 11am and we had to go to the desk to get it renewed for the remaining 50 mins.. Nothing special about the room. At least the price was right (immediately post-Covid, so an excellent rate).
At the Mantra at Sydney Airport, the room upgrade amounted to the top floor, not airport-facing, and no welcome amenities. From memory, they didn't have priority check-in.
At the Mercure Albert Park (a new property at the time) the welcome was nice (though no separate checkin) but there was no obvious room upgrade; on the contrary, we booked a room with balcony, which is what we got, but there was a huge structural pillar in the middle of the (small) balcony so there was room to squeeze in only one small chair - I'd call it a room downgrade, let alone an upgrade.
Novotel Sydney International is always nice to me and always gives me the room type (high floor, airport-facing) I request, once putting me on the premium top floor (as a Silver), which was appreciated. However, as their room rates have gone up suddenly (in the last year) by 30%–60%, I won't be staying there again.
All in all, Gold was very unimpressive. Since then I've dropped to Silver and that's good enough for me - I'm happy just with the welcome drink.