Well, ok, if there's not going to be any more hot speculative wondering about what I've chosen (there goes my ego trip. Thanks a lot, guys.), I'll just tell you.
First, some information you'll complain I should have given you up front but I didn't 'cause I didn't want to influence what was posted.
My gaming group is 7 people, most of whom are frighteningly intelligent programmer/scientist types working for Northrop-Grumman. Realism in the game world is important to them. They like things to make sense, and when magic is applied, it better be used sensibly, too. For this reason settings that don't focus on versimlitude are out. This is one of the reasons I'm abandoning my setting - it wasn't internally consistant enough to satisfy their need to feel immersed. For this reason, I am abandoning the Forgotten Realms. They would never be able to accept it as a real world.
These people are also schemers and sneakers, even when they play good characters. They are the sorts who will spot trade opportunities, political vacuums, etc and take advantage of them. Often I can't answer their questions about the intracacies of local politics in enough detail to satisfy them - and if I go into greater detail "winging it," they remember what I say better than I do and are confused when the politics of the region as a whole don't make much sense.
Also, I never fleshed out the history of my world in enough detail to make any difference. I'd like an established and more-or-less detailed history of all the lands they can travel to. When they talk to local people, I want to be able to speak in character, understanding the flavor of the local culture and how it has developed through time. For this reason, I want multiple cultures available, each with distinct and interesting histories and traditions.
My world is ending. The cataclysm that destroyed the surface will inevitably destroy the Underdark. The population is shattered. The outlook is grim. The surface races have started to tend little by little towards the darkness of the lower races. The dragons abandoned the cinder of a world at the time of the cataclysm, 800 years ago. Things are very very dark. For this reason, I don't want to bring in another dark, dismal setting. I want a world that is teeming with life of all sorts, unaffected by cataclysm. For this reason I am not going with the Scarred Lands, intreguing as the setting is.
I have chose to go with the Kingdoms of Kalamar. I already have the Atlas (oh, what a joy it is to look at) and am getting the Setting and PH soon. (I have "advance copies" from the darker corners of the internet, but I am too goody-goody to use them without actually purchasing the products.) What I have read so far is great.
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The introduction of the setting will go something like this:
Party wonders, where did the dragons go? Why are all these dark cultists trying to gather these dragon-artifacts? They gather the artifacts themselves and take them to the approprate location. A Gate opens, leading to Kalamar. The characters go through and suffer incredible culture shock. They have never seen plant life. They have never seen the sun. Their eyes feel pain in the light. For flavor reasons, I might eliminate the Underdark of Kalamar, so that the eopel of Kalamar will be confused as to what these creatures visiting them are. The characters will not know how to speak the local languages, but by that time they should be able to overcome this difficulty with magic.
They face decisions. They are an evil party. Do they tell the dying world of Tharian about this miricle? Do they use the Gate for their own gain? Wood is so scarce in their homeland is is used as currency. Do they chop down trees to make a fortune back home?
They will arrive in a sparsely settled area, perhaps the Vohven Jungle, where there is room for the sparse population of Tharian to make a home for themselves, and where they have to travel for a while before meeting civilized natives.
The players will not know I have purchased a campaign setting. They have not heard of Kalamar, I know, since I'm the most "connected" one in the group. I will let them think they have arrived on one of the tiny "demiplanes" our group has previously encountered. Except it's huge. And then they meet people. And then they meet kingdoms. And they kingdoms are fleshed-out. What is this place?
So, what do you think?