Rue 57 is just an overall great place for taking visitors out to brunch, lunch or dinner. It's central to everything and offers a varied menu with the right kind of atmosphere - half-bistro, half-NY style.
Personally, I love the brunches most, because the eggs are out of this world, especially after a late night out. They are always accompanied by a tin of crispy, skinny fries that just have a satisfying crunch and introduce the grease factor into your meal. Somehow, the day seems a little more bearable after a brunch at Rue 57. And like others have said, the space is large, so you're not dealing with harried waiters looking to have a quick turnover on the table.
All in all, a consistent favorite as far as brunch goes.