Straddling northern California and Nevada, Lake Tahoe up in the Sierra Nevada mountains is North America's largest Alpine lake and the largest overall after the Great Lakes. Much of the surrounding mountains are devoted to tourism, and in wintertime that includes 15 ski/snow sports resort areas - more than any other lift-sized area in the U.S., site of the 1960 Winter Olympics and especially strong in the area of cross-country skiing. But this year, these areas are open till...  keep reading