Start with looking at your assumption that the approach should be IP switching. Why? Who is your audience ? What countries? Etc.
Ip based switching is terrible for anyone who travels an probably only an idea outside Europe or if people live far from a border. People in border regions and in Europe who speak multiple languages will hate sites that do this.
If your target audience for sure only speaks one language. Never travels to other language areas and does not live in Europe (with the exception of possibly England) you may find it a good solution.
I just started watching a show on Netflix on Germany over the weekend and traveled an hour home to holland and now I can’t watch it any more. That’s how awesome IP switching is.
The idea of whole site switching is bad as well when you have a decent amount of graphic content and users want to switch. It’s annoying to wait for reloads. Again, Your audience determined it, not your personal preference or what google does or your grandmother likes etc.