I'm with AngHang, <sigh> about Windows on the World.
IMHO, the best of what's left is "Terrace in the Sky" (most folks just call it "The Terrace"), it's on 400W. 119th Street (between Morningside and Amsterdam). Phone: 212-666-9490, last Zagats F rating was a 23.
The location is a little "odd" but it's near the Columbia uptown campus and they have safe valet parking. The restaurant is small and intimate, often a harp player in attendance and the view is **spectacular**. It's a wonderful choice for a romantic splurge date.
regards,
fraz