When it comes to Amber, I almost always think of it in terms of Neuschwanstein Castle, because it's essentially a high fantasy castle, on the side of a mountain.
It works even better, because the view from the castle is basically on a small village below, on the edge of some water, and surrounded by forest.
Granted, the water is a river instead of the sea, and the mountain the castle sits on is somewhat smaller than Kolvir, but depending on the angle a given picture is taken from, that can be somewhat mediated. Or, given someone with enough skill, a larger mountain could potentially be photoshopped into the background.
I recently decided that the casually mentioned "well at Mirata" Brand apparently drew in one of his paintings (the one Corwin references when suggesting Brand has a "distinctive style") looks suspiciously like the chalice well at Glastonbury.http://en.wikipedia.org/wiki/Chalice_Well
I also realized just how under-utilized that particular location seems to be in Amber RP. In a game community that has a reputation for mining every last nugget (no matter how small or obscure) out of the original text, Amber-related searches for Mirata tend to turn up almost nothing.
Also, I've always liked the Giant's Causeway as a potential setting location, though it doesn't necessarily mesh with anything in the actual books.http://en.wikipedia.org/wiki/Giant%27s_Causeway