Which part of～?でも質問の意図は伝わると思いますが、「どの辺りに～？」というニュアンスなので、個人的にはやはりまだ漠然とした感じがします。
待ち合わせ場所のように具体的な場所情報が必要な場合には、
Where exactly in Shinjuku?
「正確に新宿のどこ？」
と聞くとよりはっきりとした答えが得られると思います。
ただ、会話の流れによるニュアンスというのがありますから、exactly「正確に」という言葉をわざわざ使わなくても、Which part of Shinjuku?同様に単にWhere in Shinjuku?「新宿のどこ？」でも十分通じるとは思います。
ご参考になれば幸いです。
When asking "Where 'specifically' or 'exactly' in Shinjuku (or any other place) you are asking for a precise location or directions.
This is very common when the location is big, where you arranged to meet up at. Locations such a mall, for. example. There are many stores and restaurants at a mall, when meeting a friend you would be specific as to which shop or restaurant you would like to meet at.
Example:
Friend: Meet me in Shinjuku.
You: Where in Shinjuku, exactly?
Friend: We can meet at the café we went to on Monday.
"Where 'specifically' または 'exactly' を使うことで、新宿の具体的にどこなのかを詳しく尋ねることができます。
これは、その場所がとても広く、待ち合わせ場所を具体的に決めないといけないときによく使う表現です。例えば、モールなどはたくさんのお店やレストランが入っていて、どこのお店やレストランで待ち合せするか詳しく友達に伝えることでしょう。
例：
Friend: Meet me in Shinjuku.
友達：新宿で待ち合せしよう。
You: Where in Shinjuku, exactly?
あなた：具体的に新宿のどこかな？
Friend: We can meet at the café we went to on Monday.
友達：月曜日に行ったカフェで待ち合せしよう。
Where would you specifically like to meet in Shinjuku?
"Where in Shinjuku would you like to meet?": This is asking the listener which place they would like to meet you. .
"Where would you specifically like to meet in Shinjuku?": This is asking the person to be more specific about where they would like to meet you in Shinjuku.
I hope that helps :)
"Where in Shinjuku would you like to meet?"
新宿のどこで待ち合せしたいですか？
これは相手にどこで待ち合せをしたいか聞くフレーズです。
"Where would you specifically like to meet in Shinjuku?"
具体的に新宿のどこで待ち合せしたいですか？
これは、相手に新宿のどこで待ち合せをしたいか具体的に聞く方法です。
You can ask the person where in Shinjuku where they would like to meet you. Other ways you can ask/say this:
-You'd like to meet in Shinjuku? Where exactly?
-Which part of Shinjuku would you like to meet?
「Where in Shinjuku would you like to meet?（新宿のどこで会いましょうか）」と聞けます。
その他の言い方：
-You'd like to meet in Shinjuku? Where exactly?
新宿で待ち合せしますか？（新宿の）どこがいいですか？
-Which part of Shinjuku would you like to meet?
新宿のどこで会いましょうか？
If you are planning on meeting someone in a certain area there might be many places you could meet so might want to ask whre to meet them you can simply say 'where in Shinjuku?' to get a more precise answer and to know exactly where they mean you can ask 'whereabouts in Shinjuku?' or 'where exactly in Shinjuku?'
ある地域で人と会うなら、待ち合わせできる場所がたくさんあるかもしれません。ですから、どこで会うのか確認した方がいいかもしれませんね。
シンプルに 'where in Shinjuku?'（新宿のどこ）と言えます。
より正確な場所を尋ねたいなら、'whereabouts in Shinjuku?'（新宿のどの辺りですか）または 'where exactly in Shinjuku?'（新宿の正確にはどこですか）と言えます。
At which specific place in Shinjuku would you like us to meet?
What's the exact place in Shinjuku where you would like us to meet?
Exactly where in Shinjuku do you want us to meet?
If this person wants to meet you in Shinjuku, which is a large place, he/she must pinpoint the exact place where he/she would like to meet you. He/she must mention the specific name of the place. The place may be a named restaurant, a named gas station or a named building in Shinjuku. If he/she does not give you a named place, you wll end up looking for him/her everywhere in Shinjuku and probably not find him/her.
You may ask your friend as follows:
At which specific place in Shinjuku would you like us to meet?
or
What's the exact place in Shinjuku where you would like us to meet?
or
Exactly where in Shinjuku do you want us to meet?
新宿は大きな場所ですから、もし相手がそこで会いたがっているなら、具体的にどこなのかを確認する必要があります。その場所の名前を確認しなければなりません。例えば、レストランやガソリンスタンド、あるいは建物の名前かもしれません。具体的な場所を言ってくれないと、新宿中から探すことになり、たぶん見つかりません。
友人に次のように尋ねることができます。
At which specific place in Shinjuku would you like us to meet?
What's the exact place in Shinjuku where you would like us to meet?
Exactly where in Shinjuku do you want us to meet?
（新宿のどこで会いましょうか）
When meeting with someone at a specific location it helps to specify where exactly you will be meeting.
You can name certain landmarks in the area to help identify the exact location of the meeting place.
For example, "I will meet you near the library in Shinjuku."
誰かとどこかで会うときは、具体的な場所を指定すると見つけやすいですね。
そのエリアにある何か目印になるような場所を挙げてもいいでしょう。
例えば：
"I will meet you near the library in Shinjuku."
（新宿の図書館の近くで会いましょう）
"Anywhere specific in Shinjuku you'd like to meet?"
'Anywhere specific' this is referencing or pinpointing an accurate location, or even asking if there is anywhere that they would like to meet.
"Where in-particular would you like to meet?"
Again when using 'Anywhere In-particular' this is asking if there is an exact location or ideal location there is to meet.
"Anywhere specific in Shinjuku you'd like to meet?"（新宿のどこで会いたいとかはありますか）
= 'Anywhere specific' は具体的な場所を指します。どこか会いたい場所はあるかと尋ねています。
"Where in-particular would you like to meet?"（具体的にどこで会いたいですか）
= 同様に、'Anywhere In-particular' を使って、具体的に会いたい場所があるかどうか尋ねています。
日本 
南アフリカ 
イギリス 
