SOME PEOPLE wait longingly for Christmas, others for summer, and then there are those who shudder to contemplate a dance season without an appearance by the New York City Ballet. Last year, that's just what Washington's ballet fans had to endure, and so it is doubly satisfying to have the company ensconced this week and next at the Kennedy Center Opera House.

After the death two years ago of George Balanchine, NYCB's artistic genius and guiding light, many wondered about the effect of that monumental loss on the troupe. While it's impossible to make any long-term predictions, the organization appears to be in excellent shape.

Peter Martins and Jerome Robbins, co- ballet masters in chief, are not about to let the Balanchine legacy lose any of its luster. Yet at the same time they are making ample room in the repertoire for their own and other choreographers' works.

Friday evening, in fact, marks the Washington premiere of Robbins' much-acclaimed "In Memory Of . . . ," featuring the incomparable ballerina Suzanne Farrell and Adam Luders, Joseph Duell and a sixteen-member ensemble. Inspired by Alban Berg's moving Violin Concerto -- written in 1935 as a memorial to Manon Gropius, the 18-year-old daughter of the composer's friend Alma Mahler -- Robbins' ballet is a meditation on illness, grief and the power of memory.

A second Washington premiere, Martins' "Poulenc Sonata," will be performed Sunday afternoon. One of the choreographer's most dramatically inclined works, "Poulenc" explores a young woman's relationship with two very different men.

Rounding out this first week's programs will be six Balanchine masterworks -- three to Stravinsky scores -- as well as Robbins' "The Four Seasons" and "Concertino."

NEW YORK CITY BALLET -- At the Kennedy Center Opera House through October 6. For program information, call 254-3770.