Danny Meyer’s wildly popular Madison Square Park concession stand is mobbed with hour-long lines during the summer; in chilly weather, heat lamps provide all the warmth you need. Sirloin and brisket are ground daily for excellent patties, and franks are served Chicago-style on poppy seed buns with a “salad” of toppings and a dash of celery salt. Frozen-custard shakes hit the spot, and there’s beer and wine to boot. It’s worth waiting in line for, if you ask us, but if you’re in a rush, the Upper West Side’s wait rarely exceeds 20 minutes. While the first Shack caters mostly to a working clientele, No. 2 is designed with families in mind: There’s a playroom and stroller parking.