Need some advice for Portsmouth NH trip

No, it is kind of casual…

The Library is a pretty classic steak house, but I’ve never been wowed by the seafood selection.

I’ve always enjoyed Rudis, had some of the best linguine with clams there a while back. White table clothes, piano, old school feel to it.

You might want to look at Mombo. I’ve never eaten there but have a couple of friends that rave about it.
http://www.momborestaurant.com/