My experience with registering, is you wanna register at "popular" places like Target and BRU because that is where 99% of people shop for baby items. BRU is where you will find organic items mostly (bedding, etc).
We did get a few things we did not register for and that is always to be expected too. If you have any things you don't want, you can always put a note on your registry
I just registered at BRU because I knew not a lot of people were buying us things with the exception of my parents and Brother/SIL