On a mellow day last week New York City's legions of racegoers traveled a dozen miles out to Long Island for the opening of brand-new Aqueduct, the state's long-awaited dream track—and had themselves an afternoon glittering with competition. Aqueduct proudly displayed its three new courses—dirt, grass and steeplechase—and welcomed the customers to pastel lounges, bars and betting windows. As at all fall racing openers, models fashioned the season's styles, and the ladies of the clubhouse box area put on a rival if unofficial show of their own. (Chief notes: a return of the Garbo-like slouch hat; suits and coats in raspberry tweed.) And in an even more notable rarity, Governor Nelson Rockefeller turned out for a glimpse of the racing, awarded first-race trophies. He let every track fan and voter in the place know he was there by standing out front and delivering his fighter's salute, for all the world as if he were in the presidential paddock, dreaming of a race of his own. He could also have been saying thank you. At week's end, more than $16 million had been bet at Aqueduct, the state's share of which came to just over $1,600,000.