I am looking for a modpack for BtS that contains numerous new civs to go with the ones included in the game. Any suggestions?

Welcome to CFC!

I think CivGold (http://forums.civfanatics.com/forumdisplay.php?f=217) should be right up your street.

Yea CIVGold is your best bet. be warned however as it has nearly 100 civs in its latest incarnation and can take up to 10 minutes to load the mod.

If your look for something smaller I would recommend Esnaz Mod with 28 new civs or my own Ionut's civilizations (this one however has been put on hold with the current update until my computer is replaced. However I am still supporting it and have a workaround to allow you to play the mod). I am not sure on the status of Esnaz mod as unfortunately he has moved on from modding and I m unsure of what update it is compatible with. I think it is 3.16 but don't quote me.

One thing w ith Civ Gold, is all the Civ's are "Modular".
Meaning you can pick and choose which ones you want.

All really depends on what you want, my mod is a three choice option, either Regular civ, Fantasy Civ or Sci Fi Civ, you can pick and choose which ever civ you want to play. See in my signature area. (NFW) And only takes less than 2 minutes to load.

btw Welcome to CFC.

Thanks for the advice guys. So far I have downloaded Gold and Fall from Heaven and love them both.