I don't know if it's just a few days of horrendous luck, but I've been doing the upper floors of Palace of the Dead and getting Gold sacks, only to find...

-Palace of the Dead Wall!
-Palace of the Dead Pedestal!

The things I get from silver sacks are better than gold, since Palace walls and pedestals are just as likely to be rewarded from lower tiers. Also I don't think I've ever seen a room actually use them. They're fine for bronze/iron sacks but gold should really have things like

- The native clothing (since no one really does Aquapolis since Uznair came)
- The dyeable poncho/hood/boots
- Perhaps items from past events that are now on Mog Station? It would be a great way to get them again - but still rare.