A fab day trip out would be to Georgioupoli(s) and Lake Kournas. Both are well sign-posted off the National Road towards Rethimnon. You can also do both in one day, or more of course if you wish, but there is also a little road train that connects the two for an extra bit of fun for the kids (or adults of course if that's your thing).
Georgioupolis is a stunning little town with a lovely little beach, gorgeous tavernas in and around the square, a lovely little mini-golf course and playground (which does get a little hot in the Summer), and the main attraction, the pretty little white chapel that can only be accessed by a rocky causeway. No health and safety here, you cross it at your own risk. I managed it in Birkenstocks and the kids did it fine too, but just be careful when the tide washes over your feet, oh, and look out for the lovely little crabs you see in the crevices along the way!
We've also seen weddings here, who knows if I ever did it again......................You can light a candle and say a prayer, and admire the paintings and little altar inside. Just beautiful.
At lake Kournas you can take a peddalo out for an hour or so and spot the turtles if you're lucky. Little restaurants line the front of the lake where you can grab a bite to eat, and some lovely little gift shops with some fab pottery too.