Which of the following sentences is correct? Are both grammatical?
1: I hope to see you in either France or Belgium.
2: I hope to see you either in France or [in (optional)] Belgium.
I have looked around in a bunch of different grammar books, including A Comprehensive Grammar of the English Language, The Cambridge Grammar of the English Language, The New Fowler's Modern English Usage, Practical English Usage (Swan), and various online sources and found nothing explicitly addressing this issue (I may have missed it.). Also, an Ngram shows that both are used almost just as frequently. This ELL question is very similar, but the answer has no explanation and isn't substantiated at all.
As a native speaker, I find "in either" more natural to both (or is it "both to"?) say and hear, but I'm nonetheless unsure.
Is only one of these choices grammatical, or is it just a stylistic choice?
For Sentence 2, the repetition of "in" is optional; please don't answer the question saying that the sentence is ungrammatical because of the omission of the second "in." Since France and Belgium would both be preceded (if I hadn't omitted the second "in") by "in," repeating the preposition is not required. It is merely a stylistic choice; I find that repeating the preposition puts more emphasis on the fact that the two options are distinct, so I chose to omit the second "in."