being in a private school and private school system, we are not required (yet) to teach CCSS. we count that as a good thing because we've heard almost nothing but complaints from other teachers about them.
our big emphasis has been on Differentiated Instruction, with our system paying for x number of teachers to attend the big convention in las vegas every summer. i went a couple of years ago and enjoyed it, but it can be overwhelming. the amount of time required to invest in grading and reporting (we saw an example of a report card that was insane, to say the least) was prohibitive. there are several good things about DI, most involving more than one way to skin a cat, and it sparked several ideas to try and a desire to be more adventurous in what we do in the classroom.
as for CCSS, it seems that the loudest complaint from educators is that it's only to teach to the state test, and that it doesn't seem to encourage much creativity. i don't have any experience with it, but this seems to be at the crux of what i keep hearing.