I had a lot of native platinum on my last map. I used my Legendary+5 mason to build a lot of native platinum statues. (Don't make platinum statues - it costs three times as much. Also I didn't have a legendary metalsmith or magma.) Masterpiece (native) platinum statues send a room straight to Royal, so I just spammed them everywhere and had all Royal rooms (and a two-tile bedroom with one of the Exceptional ones is still Opulent.) The higher nobles didn't like it, but well, screw them anyway - it's really hard to micromanage the "pretentious arrangements of a lesser" thoughts, and the nobles will still be ecstatic with all the other stuff heaped upon them. Everyone was ecstatic and they always had "admired a completely sublime statue lately".
It's not terribly convenient to manage who uses the native platinum, though. I built a huge room (about 10x20) and hauled all the platinum I'd mined out into it, along with some food and drink, then built a mason's workshop in it, and locked my mason and two haulers in the room, then turned native platinum non-economic and ran it until there was no native platinum left.