The only time we saw Santa Goofy greeting guests at the MK was during the Christmas party. He might have been around, but we didn't see him.
We met him in Camp Minnie-Mickey at the Animal Kingdom. He was posing for pictures and signing autographs.
You can also have breakfast with Santa Goofy at Donald's Breakfastosaurus in the Animal Kingdom. I found this little blurb on Deb Willis's site:
"DISNEY'S ANIMAL KINGDOM celebrates the yule with a little help from Donald Duck, Santa Goofy and other cartoon pals. From November 29, 2002-Jan. 1, 2003, Donald will host a special holiday edition of Donalds Breakfastosaurus in DinoLand U.S.A. For more information or priority seating arrangements for the special character dining experience, guests may call 407-WDW-DINE."
We've made arrangments to do this breakfast while we are there in December. It sounds like fun. If you call to make a priority seating, don't be surprised if the CM doesn't know anything about the special Chirstmas version. Just go ahead and make a priority seating for breakfast at Donald's. It should be lots of fun. If you really want to make sure to see Santa Goofy, this might be the best way to do it!
In fact, if you haven't seen it yet, you might want to check out this link to Deb Willis' website. It has lots of great information about Christmas holiday happenings!
http://www.wdwig.com/holiday.htm