I posted my suggestions
some time ago, but here they are again with some minor changes
UNIQUE UNITS
Portugal =
Carrack (replaces Caravel) Str: 4, Move: 4, Cost: ? Cargo Space: 2 (can carry
settler, worker, scout, explorer, missionary, spy, or great people) Can explore rival territory w/o triggering war *
Netherlands =
Swiss Mercenary (replaces Pikeman) Str: 8, Move: 1, Cost: ?
Babylon =
Bowman (replaces Archer) Str: 3, Move: 1, Cost: ? Starts with Cover and Drill I
Sioux =
Mounted Warrior (replaces Knight) Str: 12, Move: 2, Cost: ?
Maya =
Atlatl - Javelin Thrower (replaces Spearman) Str: 5, Move: 1, Cost: ? Starts with Enslave (*New promotion. Similar to the enslave ability in CivIII)
UNIQUE BUILDINGS
Portugal =
“Torre de Belem” (replaces Lighthouse) Free Sentry promotion for naval units built in the city
Netherlands =
Delta Works (replaces Drydock) +1 trade route, no
OR perhaps
Bank with some bonuses
Babylon =
Ziggurat (replaces Courthouse) +2 culture
Sioux =
Totem Pole (replaces Obelisk). (acts as sort of an extra barracks for archer units) *
Maya =
Tzompantli (replaces Obelisk) -25% maintenance OR Barbarians can not enter within city borders OR defense bonus against barbarians. Or perhaps:
Ball-Court (replaces colosseum) +2 happiness, increases the war weariness of other civilizations fighting against you
* confirmed. except carrack stats/abilities