'For most hosts, the main criterion for wines for large numbers is price,' says JANCIS ROBINSON MW. With the Christmas season in full swing, she recommends the best buys for under 6. Good-value whites include 2005 Casablanca Sauvignon Blanc (4.99; Marks & Spencer), and a red counterpart is 2004 La Serrana Tempranillo, Castilla y Leon (2.99; Majestic).