Family fare includes the internationally acclaimed clown Slava Plumin in the Off-Broadway extravaganza Slava's Snowshow (UCLA's Royce Hall, December 12-January 7); the Actors' Gang's annual offering Holidays on the Sea II (Ivy Substation in Culver City, December 2-17), and the Santa Monica Playhouse presentation of Evelyn Rudie-Chris DeCarlo musical romp All About Santa (through December 21).