In Outback Tycoon, making as much Gold as possible is the name of the game, and the +4 bonus from Gold Ore helps with that considerably. If you see Gold Ore outside your borders, found a city near it as soon as possible, then have a Prospector build a Mine to claim it as your own.
In Gifts of the Nile, you should try to claim any nearby sources of Gold Ore when playing as the Nubians, whose civilization ability will make them extremely profitable.
Civilopedia entry Edit
Though it was discovered in the early 19th Century, Australia wasn’t sick with “gold fever” until 1851. So much gold ore was recovered that Britain opened the Sydney Mint, the first time British coins were allowed to be struck outside of England. Gold has consistently remained a lucrative Australian export.
Gifts of the NileEdit
The Nile people derived great wealth from gold ore in their lands. Though Egypt claimed numerous sources of gold, its pharaohs and priests always hungered for more. Nubia's abundant gold mines to the south were a constant point of contention between the two civilizations--Egypt wanted them, and Nubia refused to provide them.