The Emporium is huge and has a general mix of stuff. If you are looking for more selection of one specific theme/character/attraction, then check out the attraction gift shops. We love POTC ride and the movies, so we've bought lots of stuff from the gift shop at the Pirates ride over the years. If you want a splash mtn shirt or Brer Rabbit plush, check out the gift shop at splash mtn exit. Sir Mickey's had princess themed stuff recently, I specifically remember cute Ariel stuff and the "dinglehopper".
I love disney coffee mugs and attraction specific tees/tanks. My DD has always loved smaller plush. I'm not sure what's considered "rare" plush right now, but she did get the plush dog from the pirate's ride holding the keys at the pirate's gift shop. This was several years ago, so not sure if they still sell it there.
The Christmas Shop in Liberty Square has has lots of ornaments. You can have one personalized. And I've even seen some available that come already personalized so if you like what they have, it can save time waiting for your personalization or having it sent to you.