This is the first year I'm focusing on more uncommon games. I've basically been looking for games that are common enough, but not big enough to have a whole booth.

Celestia is a game I'm pretty interested in. The main issue is, the creator/publisher doesn't seem to have a booth.

This is the case for other more uncommon/less talked about games as well. I'm having trouble finding the booth for Rampage/Terror in Meeple City.

So I guess I'm wondering if there were any clues ahead of time as to who will carry what or if I'll just be hunting through booths and random distributors like usual.

There have been booths in the past that had a mixed bag of games but not sure their names or if they still come to Gen Con.  You may have better luck in the auction. 

Isn't Terror in Meeple City an Asmodee game?  I seem to remember them carrying the game at Gen Con 2014, and Asmodee is listed as the producer on the game's Cool Stuff Inc page.  You'd probably find that one there.

Game library?

Did you get in touch with the publishers?

They should be able to tell you if someone's bringing their game to GenCon.

Terror in meeple city is Repos Production. Not sure if they have a booth or not, but I agree ask the publisher if they will be bringing certain games.

Asmodee is the parent group of the publisher for Terror in Meeple City. They have a large area and a giant sized version of the game. Seats at their demos are in high demand and often hard to get. The best way to make sure you get to play some of those games you want are to find events where they are being played and get a ticket or show up with a generic.