As Mukunda has mentioned, there are so many ashrams throughout the world, each offering a unique set of teaching and practices to their students, most of which will guide you through a different lifestyle and spiritual pursuit. It really boils down to what you want to accomplish and also where you want to study.
If you want to go back to the source, the best place to consider is India. Why? Because the culture provide a conducive environment that enforces the spiritual practices and philosophies outlined by the yogic system. Cultural psychology typically differs from one country to the next, and the mindset of the society is a vital influence upon the individual and their choices and pursuits in life.
India is traditionally a spiritually oriented society in which people are inclined towards spiritual practices and techniques. Aside from this, the yoga teachings are enforced by the culture which views spiritual living as a noble and just pursuit.
In the past I have studied at the Tureya Ashram in Kodaikanal, which is located in Southern India. They offer the traditional science of yoga which educes spiritual insight and experience, something I have not been able to learn in the yoga courses I have taken in the US, Germany, and Canada.
But again it boils down to what you need and the path you wish to pursue. This is just my experience and opinion as one who has wished to find the truth of spiritual living.
