NYC -- Broadway, dining, art museums, shopping
The Greenbrier -- so luxurious, great spa, great golf (Tom Watson is the pro), beautiful scenery, even has a bowling alley
The Cloister -- so luxurious, love the way they spoil you, love getting dressed up for dinner, bingo, macaroons and milk afterwards, the 60's bands and dancing like being at an old-school frat party, the general manager's party, the cookouts and the Nutty Buddy man, the lunch buffet with all of the fabulous shrimp and everything else you can think of, love the spa (warning: the beach is like a parking lot)
San Diego/La Jolla -- great views, great restaurants, great golf, artsy, so funky that I didn't want to come home
Chicago -- great lake views, dining, shopping, love the A.I.A. architecture tours, the Art Institute of Chicago
Dallas -- have always loved this town (guess it has something to do with being half Texan), love the dining, shopping, cowboy boots, the swagger
New Orleans, Maui, San Francisco, Lake Tahoe, Charleston, Las Vegas, and Tucson are also on my list. And if you have kids, you must go to Disney World.
Outside the US my favorites are Italy (in particular, Florence, Rome, and Cortona), Barcelona, Paris, and Tokyo.