I just added a patch for the country field:
http://ubercart.org/issue/1601/country_field_shipping_estimates

I did not add zone, but it would be trivial to do. Personally, I think the less information a customer needs to enter, the better.

A great modification to this would be to use one of those IP<>country lookup services, and default the country to the detected country (though, that may be better done in uc_country_select() )