We saw Mulan at Goofy's Kitchen (character breakfast) in Sept.
We also saw Ariel, Cinderella, Sleeping Beauty, Belle and Snow White at Ariel's Grotto (princess character lunch). But they can also be found at Princess Fantasy Faire throughout the day (usually you can meet 3 princesses and they rotate throughout the day).
We also met Rapunzel at her meet and greet in Fantasyland...and Jasmine and Aladdin at Aladdin's Oasis in Adventureland.
Then we also saw Tiana (as well as all the other princesses I mentioned, excluding Mulan) in Disney's Soundsational Parade.
You can also go to City Hall and they can tell you where to find a certain character that day.