Any recommendations for restaurants in Cinque Terra?

For Monterossa al Mare:

View - Hotel Porta Roca, you will pay for the view. Low key as well, but upscale.
I'm not entirely certain there is a single venue to meet all your criteria. For great food, L'Osteria. Belvedere may be the closest to meeting all your points.

I need to understand what you mean by "fun"?

In Vernazza, try Belforte for the view & food.

Monterosso: Cantina di Miky. Ask for a table outside on the beachside/waterside deck.
https://www.cantinadimiky.it

https://www.facebook.com/lacantinadimiky

https://www.tripadvisor.com/Restaurant_Review-g187820-d2213377-Reviews-La_Cantina_Di_Miky-Monterosso_al_Mare_Cinque_Terre_Italian_Riviera_Liguria.html

https://www.yelp.com/biz/la-cantina-di-miky-monterosso-al-mare

I second Cantina di Miky!

Thanks to all that replied- we are staying in Manarola. Should I make lunch reservations too?
And, if so, any thoughts?