As my friends and I strolled in, we went straight for the Laurent Perrier champagne bar; it is stunning, with views from the 25th floor. The bar adjoining the main restaurant has a brilliant cocktail list and sharing platters, but again, visiting for drinks is acceptable.
Seating is plush, and although there were only three of us, Marco's accommodates larger groups with plenty of cube-shaped seating around smaller tables - enough to fit your drinks on - so don't worry if you're drinking with more than a few friends.
Now I said my friends and I only visited for a tipple or two, but Marco's have a secret weapon: the dessert board. It is huge. We couldn't resist the the marmalade martini (as good as it sounds), and I urge you, get there for sunset for the best view in town.