Henry Roth   New York Magazine Pick   The Collection: Full silhouettes and bold beading evoke Hollywood glamour—at non-Hollywood prices. After stepping out from the house of Michelle Roth last year, brother Henry has introduced a line of grand, shimmering dresses—many with his signature plunging backs and necklines.   The Gown: Princess dress with corseted lace-up back and Swarovski beadwork.   The Price: $1,200.   Where to Buy: Gowns range from $1,200 to $1,900 and can be purchased at Kleinfeld.