Goofy can be found all over the Disney Parks and Resorts.
At the Magic Kingdom Goofy can always be met at the Silly Sideshow. At Animal Kingdom he appears at Camp Minnie-Mickey and Dinoland USA. In EPCOT he be found in the Character Spot. At Hollywood Studios he can be often met around the Big Hat.
At Disneyland your best chances are up in Toontown, or in Town Square. Over at California Adventure you can meet him usually meet him on Buena Vista Street.
At Disneyland Paris Goofy regularly meets aboard the Celebration Train, or up by "it's a small world". in the Studios he is often found randomly wandering around.
At Tokyo Disneyland, Goofy is often out in Toontown, and in just about every land of DisneySea at some point!
In Hong Kong Goofy can often be found in Fantasyland at the Fantasy Gardens area, or on Main Street.
On the Cruise Line Goofy appears at select times. Check your Personal Navigator for details.