Spring Style; The Look of Choice

If Seventh Avenue isn't selling short for spring, it won't be for lack of trying. Little above-the-knee skirts outnumbered long lengths by at least 2 to 1 during the big second week of fashion openings here. While most collections had both extremes, the so-called average hemline wasn't around. When it comes to next season's lengths, your leading designer is not Mr. In-Between.

There isn't a middle-road consensus on shape, either. The kind of curvy fit that was dismayingly prevalent in some European showings turned up at several New York houses, yet was totally absent at others. Garish prints and high-visibility colors had a lot of exposure - but no more than neat, clean patterns and muted, conservative tones were given. The same sort of taste gap applies to jewelry. Oscar de la Renta loaded on the beads and baubles. Calvin Klein's models wore no jewelry at all - just wristwatches.

It will be up to the customer to pick and choose her own warm-weather way of dressing, which can be variable or constant, depending on the needs or mood of the individual. No one can say there aren't enough choices.

Although minis and walking shorts walked away with the honors, mid-calf gathered skirts, sarong wraps, and pants are in there too as modish alternatives. Cotton-knit blousons and sweater sets with intarsia patterns that repeat print motifs of companion skirts (specialties at Adrienne Vittadini) are options for those who'd like a change-off from a linen suit for day. Playing the updating game by mixing new separates with the old should not be a problem. Among the possibilities: the giant-plaid madras pieces and primary-color cottons by Frank Smith for Evan-Picone, Middle America's favorite.

The top of the silhouette - a carryover from fall's mannish look - continues to be loose, large, and for the most part elongated. Some oversize jackets, like the ones at Perry Ellis, have hefty shoulder pads and lines that hark back to the stroller coats of yesteryear. Padding is also added to a lot of the camp shirts which appeared everywhere, often elevated from their lowly status to the charmeuse league. At de la Renta, they were beaded with glitter and worn with long satin skirts. The T-shirt had similar treatment at Bill Blass, with satin minis. But it is the big shirt - as a top, a dress, or in duster coat form - that is the focal point, day or evening, for the new ultra-relaxed sportswear dressing.

This style reached its apogee at Calvin Klein, where long means almost to the ankle and short means Bermuda length. Concentrating on expert cut and fine fabrics, he has condensed modern dress to its essentials. Colors are classic navy and white, quiet neutrals, or face powder pastels. The only decorative concessions are in textural contrasts - linen twills used for walking-short suits, pants, and skirts, combined with hopsacking and hand-knit cotton, for instance. Knit minis composed of bands of contrasting stitches were worn with white tights and Manolo Blahnik's low slip-on beige shoe. The big shirt in organza, with matching sash tied at the hipline, was a refreshing look for the let's-dress-up occasions.

In the same contemporary vein, Ralph Lauren limits his sights to quality and easy luxury. Whereas Klein's simplicity can verge on the austere, however, Lauren always keeps a romantic edge. White sheeting for billowy shirts and side-wrapped skirts (of both going lengths), combined with linens and silk tweeds for sumptuous jackets, are set off by his new floral print - a soft-toned blue or old rose-grounded pattern that recalls the kind of aged chintz found in a favorite summer house. No gaudy jewelry needed here, either. His halter-topped dresses are worn with handsome belts, but that's all.

Not so simon-pure in his approach, yet still on target for the woman who likes her clothes beautiful but not blatant, Geoffrey Beene is at his best. His choices include long, belted cardigans over short skirts and cropped boleros with full skirts, plus dress and jacket costumes in Roman stripes, with the fine piping that is a hallmark. Chemise dresses are never humdrum. Nor is anything else. What sets Beene apart is his eye for subtle relationships between fabrics and colors and a near-couture sense of the telling detail. A band of gray satin on a silk skirt picks up the touch of satin on a jacket; the unusual diagonal cut at the back of an otherwise unadorned little black dress takes it far from the ordinary.

Would that such restraint were exercised everywhere, but alas, the skimpy dress that was shirred like one of those Austrian window shades and clasped every line of the body was a commonplace in other collections. So was the big candy-box bow, on the hip, on the shoulder, on the derriere - sometimes all three places on a short strapless dress.

Shorts, which shaped up as a major trend, would seem to have a more viable place in spring fashion. Kasper said he liked the new full-cut Bermuda lengths because they are ''fresh, alive.'' Presented with matching jackets - the safari styles at Evan-Picone were one example - walking shorts will probably make it to city streets as a youthful change from the conventional suit. They will be there for dressier times, too. Both Lauren and Zoran, the minimalist whose influence is felt in the clean looks of next season's offerings, showed satin Bermudas.

Meanwhile, reports from Europe tell us designers there are trying out the idea of skirts for men. So cross-dressing is still in the air, even if the word ''androgyny'' is phasing out of fashion's vocabulary.