There are loads of character sightings in the park, but they are all beyond reach. You won't see them walking around at all. At EPCOT, they'll have characters out on the grass beyond a fence, but you can see them frolicking and playing.
At Animal Kingdom, they ride around on boats. Hollywood Studios and Magic Kingdom have "Cavalcades" with characters riding in cars. And you can see characters waving from rooftops at many locations in Magic Kingdom and Hollywood Studios.
The characters are still present, but you can't get close to them.