By Lenn Thompson, Editor-in-Chief Merlot very well may be the signature red variety of Long Island, but if someone were to ask me to pick a single red grape that is successful in all of New York's major wine regions, it has to be cabernet franc. From Long Island to the Hudson Valley to the Finger Lakes to Niagara and Western New York, there are well-made francs to be had. Standing Stone Vineyards, on the eastern short of Seneca Lake, produced this Standing Stone Vineyards 2007 Cabernet Franc ($20) with grapes from the original Gold Seal Vineyard (read more). Raspberries…