I think I am in agreement with Els there, though I wouldn't say I was really excited about Falun, but the reasoning is sound.
Guanajuato - I'm trying to think if it can get a place here, or whether Potosi covers the same ground better. However, the urban landscape is impressive and unique (better than Kutna Hora in my view), the churches up in Valenciana show the extreme wealth being pulled out of the ground next to it and also it is just a brilliant, brilliant place to visit.
Of the none standard ones. (though I'm not going to stand up for them too much):
Las Medulas - perhaps worthy of consideration for showing the after effects of mining?
Spiennes - is a pretty unique site in terms of it's age, so I will show it a little love. | 
