This is somethingg GC2 did well, that hasn't popped up in Elemental yet.

Things that should be options:

a) sliders for each category special resouces: shards, mounts, food, pits, iron, gold, libraries, shard, temples.  In addition, have 5 bins for modded resources so modders can have custom levels for custom resources.

Your standard terrrain modifiers- which should be something that emulates Civ.  Civ does it better then anyone else

c) Land/water modifiers, again similar to Civ 4.

d) Maybe a slider for balance (making sure everyone has a similar start) versus variety.  choosing balance may disable things for MP, whereas variety would allow for a better SP experience.

e) A set of sliders for goodie huts and quests by level.

f) A slider for indies, like what GC2 had

Unsure what else would be needed.