Telascica and Dugi Otok are not a short boat ride from Zadar. Far from it.
Nin doesn't need a day.
Krka NP is a good idea. You can catch a bus to Skradin and back after you finish. Allow all day there. If you only spend a few hours and don't do the optional boat tour to Visovac at least, you might walk away disappointed. If you need more info, please don't hesitate to ask.
Visit Sibenik. It is a very charming old city.
You could do Plitvice, but don't do it on weekend. Again, catch a bus there and back. Allow about 6 hours at Plitvice.
For bus timetables and bookings, check buscroatia.com
If you need mor help, just ask. I know the whole area like the back of my hand.
Just adding.
You could even visit Split as a day trip, if you haven't been there before.
Cheers
Edited: today, 06:17