Integral Yoga Institute: it's actually an Ashram in the middle of NYC, they offer a large variety of classes, more Hatha oriented, very high quality, peaceful and serene atmosphere. They also have a regular schedule of events such as Kirtans with great musicians, workshops and trainings. One of my favorite studios!

Yoga Works: I found consistently great teachers, mainly following the Iyengar and Vinyasa approaches but also offering less traditional classes such as Urban Zen and Yoga Tune Up.
They have a full schedule of classes and several locations.

Ashtanga Yoga UWS: small studio big heart! The owner, Zoë Slatoff-Ponté, trained with Sri K. Pattabhi Jois for 10 years, offers Mysore Style Ashtanga classes, and is always in class! Very authentic, no frills, real value yoga studio. Prepare to sweat and to have break through with your practice!

Iyengar Yoga Institute NYC: this studio definitely stands up to its name. Their classes will deepen your practice, offering new ways to approach and postures and to feel their alignment principles. Very interesting, especially if you are a yoga geek like me!

Jivamukti Yoga: this studio has become famous worldwide for the specific style of yoga that its founders Sharon Gannon and David Life developed. They offer classes for every level, mainly following a Vinyasa approach. Excellent Yoga and definitely a unique NY experience!