I like the second one best because it shows the whole world, not just the North/South American half, and I think it's so important for kids these days to have that "global perspective" -- even if they don't realize they're getting it.

As for the bottom left, I think the school year and the name of the school would be a nice touch, and also, under the signature line, I think you should type in your husband's name and title, i.e. Mr. Skiles, Geography Professor, and if you could get one of those imprinting stamps like a seal, that would be a fantastic touch! I think you might be able to get them at a stationary store or hobby shop type place.

Great idea to recognize the outstanding students!