Hi, Diane! While characters are subject to change without notice, I can tell you that as recently as about three weeks ago, Goliath, the lovable lion from the Playhouse Disney classic show JoJo's Circus was not appearing. You will still find the characters from the Little Einsteins, however, joining them was Handy Manny.
As for the character appearances over by Toy Story Midway Mania, outside, you can find the Green Army Men, and inside the building, you might see Buzz, Woody, or Jesse. If you go a bit further down the street, you may run into Mike and Sully from Monsters, Inc., or JoJo and Goliath from JoJo's Circus.
Your best bet to see who will be appearing where on the day of your visit, you can ask the cast members at the theme park when you arrive. They will have the most current information available, and they will be able to give you an idea of where to go at what time to see some of your favorites!
Have a great vacation!