Russian food would be too close to German food, IMHO. As I am Ukrainian, we have always avoided the Germany restaurants because we can go to my grandmother's and get very similar cuisine.

Africa would be nice, but there is AKL. I vote for South America (Peru, Brazil, Argentina?)

Lately I've had a hinkering for Greek food, throw in some mythology and history and a Greece Pavillion would be awesome. Might be difficult to get Greece to invest right now though....