So, many apologies for the lack of replies. I had been quite busy since about the thirtieth, and then when I was just about ready to make the post... frakking site had to go down.
As much of this is going to take place in The Underdark, it's either Greyhawk or Forgotten Realms. I usually prefer Greyhawk, as boring as some of you may find it, though the actual area will be homebrewed; The Underdark does, after all, span pretty much around the entire world, so there's plenty of room for some custom places. I planned for our first adventure hook to be a fetch quest, sort of. Abstersine had found out about an inquisition of mind flayers that had been kidnapped, restrained and debilitated by a group of githyanki. Whether or not it's a good thing that the githyanki found them instead of the githzerai is questionable, since at least the githzerai will kill them quickly.
From there on, how things go with how well you guys handle this first bit will help me determine which part to do next, since I do have a few different branches in mind to follow.