It was not so much an embarassment as an extravagance of riches to have had both the New York City Ballet and the Paul Taylor Dance Company performing in Washington this weekend. It was an accidental conjuction of the best of the best of two worlds - classical ballet and modern dance - and it doesn't happen often anywhere to say the least.

To Lisner Auditorium Friday night, Taylor brought his most recent, not-quite-finished (it was called a "work in progress" on the program) opus "Images," set to Debussy piano pieces, including portions of "Images", "Children Corner" and "Pour le Piano."

The modular costumes by Gene Moore, the ghostly lighting by Mark Litvin and the choreography itself conspire with Debussy's exoticism to give the work the look of an Egyptian frieze come to life. At first viewing, the inspiration doesn't appear to be uniformally sustained througout the eight movements. The imagery is so striking, however, and the mood so consistently haunting that it is the power of the more successful sections at the start and finish one comes away remembering.

These include an opening huddle of dances, emerging slowly and starlingly into light; a frieze-like procession of figures behind a rear scrim, bodies slanted and in half-profile; and the final circular formation suggesting a blazing sun, giving way at the end to a lone couple in supine embrace. The whole dance is like hallucinatory scenes ofancient worship.

Despite the rigors of an extended tour, the Taylor dancers were in superb form, dancing with fusion of vim and resonance which has become a company trade mark. Also on the program were the compelling "polaris", first seen here last November, and the mordantly witty "Public Domain," stalked by John Herbert McDowell's brilliant musical collage.

The Maryland Dance Theater, the statewide touring troupe based at the University of Maryland and directed by Larry Warren, danced its spirited way through an ambitious program of seven workds at Tawes Theater Saturday night.

There was no lack of competence, either in the performance or in the dance material. Art Baumann's "Errands", with its humorous false starts and inventive use of props, is both interesting and orginal. Bill evans' "For Betty" which is imitation Paul Taylor but skillfully wrought, and Dorothy Madden's "Widow's Walk," a slender but evocative portrait of a lonely vigil, are a cut above the norm in choregraphic craft.

But "Earthrush," and "Nighflight", which had a disturbing erotic under-current when danced by their choreographer, Diane Baumgartner, see> to have lost their intriguing qualities in transfer to other dances. And neither Anne Warren's pallied, pretty "Dance in Red," nor Vera Blaine's sight gags on highway signs, "1-71," had much to offer. As a whole, the program suffered from a distressing blandness of tone and content.

No two dance performances are ever quite the same, but sometimes the differences can seem strangely vast. On Thursday evening the New York City Ballet gave Jerome Robbins' "Dances At A Gathering", and then repeated it Saturday afternoon with the same cast. On the first occasion this testament to poetic companionship seemed slight in substance, and the dancing, through secure, looked perfunctory. On Saturday, though, the dancers seemed caught up in a wonderous lyrical rapport, and the ballet itself was by turns rapturous and beguiling. That's the magic of live performance.