Definitely take walks around Strawberry Banke and Ordione Park in Rye, window shopping downtown is always fun too. Best food depends on what you want, Massimos is the best Italian in NH, lexies and brgr bar have top notch burgers and Martinghale Wharf is good food with a view, I love the puddledock for english food.

The Wilder is great for cocktails and a quick bite. Dessert at popovers. See a show at either the Players Ring or Seacoast Rep. walk through Prescott park/Strawberry Banke. There are a few interesting oddities shops if you’re feeling like browsing in a spooky setting: deadwicks ethereal emporium, fezziwigs food and fountain, pickwicks mercantile. And the friendly toast for breakfast if you’re staying the weekend.

Just to see how many folks know old seedy Portsmouth. The fifth wheel or the midnight reader.

I’m jealous. I don’t know shit about Portsmith but I could really use some time without kids.

Eat, walk around seeing the sights, shop. At some point walk across the bridge to Kittery foreside for more eating. Make sure to walk around prescott park and strawberry banke. Not sure if the docks are still open, but if so, try to get a table at one of the waterfront restaurants. Maybe take a boat tour around the piscataqua, there's one that goes up-river for foliage, but there's a couple others.

Look at FB Seacoast Eats and search "Portsmouth" for restaurants. Hundreds of recommendations.
TripAdvisor to see what boating companies are still open. If weather decent, you may want a boat ride.

Go to a show at the Music Hall Lounge. Sit in the window at the Portsmouth Brewery and have a beer or two and people watch. Have dinner on the patio at the River House.

And when they're grown and gone you'll wish they were home. But they call it the circle of life for a reason.

No doubt.