I don't think that coasts needs to be plural. The only time I would use the plural is wben two or more specific coasts were referred to e.g. the east and west coasts. Otherwise I think the coast of France or wherever would suffice.
It is possible because "les côtes" is discernible as plural. However, in English, one would be extremely unlikely to say the "Portuguese coasts", since, after all is said and done, there is essentially a long west coast and a short southern coast.
I thought that when something was "new", i.e. made from scratch and not a "new" dress, that the word was either "neuf" or "neuve" and that it was placed after the noun, like le pont neuf. These hotels, I assume are recently constructed.