I've seen structures where the grouping is by continent or sales region
first (americas, emea, apac, for example). That would also be a better
organization to lock down users to have access for one single market only.
So do you then break it down by language? So it's foo/americas/en?
JE - What are the considerations in terms of live copy and translations. Both of them play a major role in defining your site strategy and structure.
I work this structures by a combination of country-language, all with ISO standard. Example en_US, es_US
you can name the site whatever you want. To my knowledge importat thing in terms of multi-language support is the site language specified in properties. You may not see the difference in built-in languages (de, fr, es, ...) but once you try to switch to something that is not there out of the box and use the translator to manage keywords you will see the difference. If you have issues with EN-UK and US and others I would go with structure that Rudy pointed out
and it is up to you if you use short iso codes or longer description. Just make sure that you specify the site language in site properties (advanced tab)
Hope this helps a little.