We've been a few times to Zadar - absolutely love the old city and its sea organ
Stayed in small villages around, one of them was for sure Bibinje, the others don't really remember the names, we just searched for accommodation near zadar on booking.com
we were usually going to the queeens beach, my husband loves the mud baths there too, here's some info on that, it's not far from zadar
http://www.zadar.hr/the-queens-beach/
we visited Plitvica lakes and Krka park, both are amazing and Zadar was a good base for exploring those
Split was nice but very very busy
Enjoy your vacation!