[DoubleCribble]

The number-one-most-powerful tool that I can recommend in teacher development is getting mentored by a Master Teacher once you are in your own classroom (ie, not student teaching). The good news is that you will likely get exposure to many/most of the big ideas in any graduate program. However, it's very difficult to integrate those big ideas into your own classroom without a guide. Having somebody regularly observe your work and hold you accountable for your choices can make an enormous difference in outcomes (and often very rapidly). If a formal mentorship program is not available, then I would recommend seeking out an informal one.