The travel editor for Ski magazine and author of Ski Guide to Europe recently discovered that while ""Europe is great. So, at last, are we."" And this is directed at the large percentage of enthusiasts who are likely to pack up for a ""Ski Week"" winter vacation. Miss Rand is a savvy, very thorough, investigator who tells you what to expect and how to get there. She includes tours, plans and packages, costs, reservations--""the hairiest form of ski competition,"" slopes and slush, apres-ski social life, shops, restaurants and services. From Alta, Utah, which ""has the best lift-served skiing in the world and that is a conservative statement,"" to swinging Aspen to Squaw Valley, Stowe, Sugarbush, Sun Valley, etc., this will give you a lift even before you're started.