My proposed solution would be to not have such a "landing page" blocking me (or crawlers) from visiting the site at all. Look at how Youtube does it - they add an (annoying) element to the page asking for whether I would like to "fix" my location.

I surf with cookies and Javascript disabled by default, so unless your site was the only site returned in a search and immediately relevant to my interests, I'd never go beyond your "Choose your language" thing.