You might want to do some research on windshield treatments before you go too far. Some of them are extremely difficult to remove if you decide you no longer want it.
For inside and outside of all my windows, I use a mixture of 3-4 drops of Dawn in a 32 oz. bottle of water. Works great and leaves no streaks. Use it just like Windex.
I use Rain-X on both inside and out. Apply with a paper napkin, wipe with a damp cloth then buff with a clean microfiber. The glass is perfectly clear, no streaks and cleaning in between Rain-X applications is MUCH easier.
I like Stoner's Invisible Glass, it's an aerosol and cleans very well without streaking; you can order factory direct or get it from your local auto parts store.
I wouldn't use RainX on interior, it just seems like a waste to me, there won't be any water on the inside (hopefully).
Just 2 more cents for you.