The border kingdoms (assuming I'm thinking of the right ones) may be a bit too tropical, being on the shining sea and all.
Personally, I'd take the Great Dale (p201 in the FRCS if you're interested) and change the flavor a bit. Make the ruler your Strahd instead of a reclusive druid in a living wooden castle that kills all visitors. The rest really is just a minor adjustment in tone to make it more gothy and you're set.
You've got your big forrest, mountain vale, introversive rural folk, plenty of room for gypsies and oodles of horror. Plus the climate's right, and it's sufficiently remote.
Hell, come to think of it, I may just do this for my game as well...