[Matt Droz]

See, I didn't use sub-races or ethnicities for the elves, dwarves, gnomes, halflings, etc. I simply had the user choose a race and, if they wanted to do subraces, I added them in as Alternate Racial Traits. The default races are the ones where no changes were made (i.e. Moon Elf, Shield Dwarf, etc.), and if they wanted to be an arctic dwarf or avariel, then the alt race trait makes the changes. Ethnicity I only used for the humans, since it's mostly descriptive, but is required for some character traits.

How are you handling the Cleric prestige classes like Stormlord and such? I created them as archetypes instead of a prestige class, giving the players a bit more flexibility so they aren't playing to get to the specialized class. The biggest difficulty was figuring out most of the domains, I agree. Most of the time, I just ignored a special ability for the domain and just gave them a good spell list.

Similarly, I changed most of the regional feats to character traits, since they were basically the same thing.

One last thing that I found really great was integrating the Mythic Rules into the Realms, since I was able to build Elminster to his FRCS stats using base Heroic NPC stats and the Mythic abilities. The unfortunate part is that there were a few items that only load if the player has other data packages (like Mythic or Ultimate Campaign).