Ali is biased but Newburyport is a pretty perfect town. It's a historic seaport city with a lot to do: stroll along the waterfront boardwalk, go to Oldies flea market, and shop up and down State Street. For food, get lobster/lobster rolls and other seafood at many of the great restaurants in town including Michael's Harborside, The Poynt, or best of all and a little down the road, the lobster shack Bob Lobster. For a drink, try the iconic Newburyport watering hole, The Grog, as well as the Thirsty Whale, Paddle Inn or, just across the river, The Deck
Plum Island is a gorgeous beach community definitely worth a beach day, or at least a long walk. For food, try Mad Martha's for a life-changing brunch, or Plum Island Grille for great food and a famous sunset view. The aforementioned Bob Lobster is also on the drive to Plum Island if coming from downtown Newburyport.
Obviously, if you're from out of town, you should explore Boston! If you're staying near the wedding, the train from Newburyport to Boston's North Station is convenient and takes about an hour.
Like witchy stuff? In need of some herbs to burn in the house to annoy your partner? You might like Salem. This is a fun little town with a lot of history, restaurants and cute shops.
Maudslay is a beautiful state park, perfect for a long walk in the woods. There are a lot of different pockets of the park with cool things to see like river views, remnants of ruined antique houses, and flower gardens.
If you're like Rich and see the world as your brewery tour, this is a great one with delicious food. For other awesome breweries, try Riverwalk in Newburyport or Notch in Salem.