There's a number of Alice characters in the park. Most often, you can find them near the Mad Tea Party, but they appear other places sometimes as well. Sometimes Alice appears in the Toy Shop in the UK pavillion at EPCOT. And also as previously mentioned, Alice and the Mad Hatter appear at 1900 Park Fare's character breakfast which is excelent.
A lot of the parades around the parks feature characters from Wonderland too. Alice, the Mad Hatter, and the Tweedles are in Disney Dreams Come True at MK, Alice, the White Rabbit and the Queen of Hearts are in SpectroMagic, and Alice and a few others usually appear in the Disney Stars and Motor Cars Parade at MGM (it was just Alice and the White Rabbit when I saw it last, but I've seen the Hatter in it too).