The gold poster is gorgeous on so many levels. I suspect that the silver is equally gorgeous but just loses something online. I've seen silver on black paper before and it's quite stunning with how it works with the light.
On a design level, I really love how these look extremely architectural. Almost like an extreme close up view of a city by day vs by night. Or maybe one is summer and the other winter.
How heavy is the paper? Telling me weight or stock number won't say much to me so I guess you'll have to use words somehow. Hope you went with a heavier, sturdier stock. These are really some fine works of art.