The same way we complain about the value of testing measures for students, teachers need to evaluated organically too. There is no simple way to do it. It will take time to make it meaningful.
There should be several observations with immediate feedback and recommendation and praise with not just assistent principal and principal but intervisitiation or outsiders who don't the teachers so that objectivity can play into the equation.
The measure and standards for which we are being evaluated need to be made clear before being assessed to eliminate the "gotcha" mentality. Transparency is key.
There needs to be flexibility to account for individual teachers and their success based on their own personality. Not a cookie cutter, everyone should be doing the "workshop model" everyday mentality for example.
I wouldn't be opposed to parents having a voice in this process too as theirs is an important voice a child's education and relationships build between schools and families are essential to whole student/person success.
Students should be allowed a voice as well... they are, afterall, who we serve as teachers. If we are truly catering to them in a multifaceted, differentiated way, we shouldn't fear their feedback, we should welcome it.
Maybe the final piece is portfolio - maybe teachers should put together a portfolio of best practices/lessons/assignments - examples of student exemplars on those assignments - examples of feedback and assessment measures as well as self-reflective pieces. Parental outreach and professional development measures should be in there too.