The other nation I would like to see:
The Mapuche Nation (of Chile and Argentina)
They were the only indiginous people of South America that stood up to Spain, and were actually granted a letter of independence.
Special unit: Toqui (axe-bearer).
Read up on them here:
http://www.mapuche-nation.org/english/main/feature/m_nation.htm
or here:
http://en.wikipedia.org/wiki/Mapuche
to find special traits for them.
A special kind of hospital would be nice, as they had/have some great healers, or a special court of law (they had/have a very orginized society). Or maybe forests yielding more labor, as their "national tree" is the Araucana, the Monkey Puzzle tree. Or that last one could be made to replace levee/dike - grow (build) an Araucana and forests/timbermills/national parks yield more labor.
They could also be used as an introduction of a new religoin - shamanism, with a Machi (spiritual leaders that function as: witch-doctors (curandero), and/or herbalists, religious authorities, and consultants) as missionary.