There is not a whole lot happening most times in Salem, but any visit must contain a trip to the Salem Witch Museum and The House of the Seven Gables . You can walk through Pickering Wharf to find some neat witch craft items or art galleries. There a famous chocolate candy maker Harbor Sweets . They make delish candies in the shape of nautical items. Sweet Sloops, Sand Dollars, etc.
Head up early morning and you'll have more than enough time to do everything. Park in one of the main lots and walk.
You can always take US 1 back to Boston and eat at the Kowloon Restaurant in Saugus, MA
Having lived all my life in NH, I need to be completely honest and say that Salem is not a place that I know anyone would plan a destination/visit to. It's not a bad place, but there is nothing of history, value, culture there. Only a large shopping mall frequented by people from Massachusetts and an old dog racing track. Being one opinion of many, save your money and visit somewhere else (no offense to anyone from Salem). If you are planning to visit Salem NH for other reasons, then I understand, but it's not a 'destination location' within New Hampshire. Now, if you wanted to consider Salem Massachusetts, that's a different story! Salem (Massachusetts) MA is chock full of history, folklore, architecture, and pleasantly located along the historic MA waterfront, this would be pricey to stay if memory serves- There lots of bed and breakfasts here.
If New Hampshire is somewhere you want to visit, I strongly suggest Portsmouth NH. Again, loaded with history, architecture, cuisine, and also along the small but beautiful NH coastline, the cost for a trip to Portsmouth is probably going to be less than Salem MA.
Salem is a great place to stay and visit Boston, instead of the other way around. . . it is a lot less expensive than hotels in Boston for sure. The commuter rail takes 29 minutes from Salem Station to North Station in the heart of the North End. There is a lot to see in Salem, especially the PEM (Peabody Essex Museum) and The House of the Seven Gables. You can also take the ferry from Boston to Salem in the summertime. Salem Station for the "T" is only 3 blocks from the Hawthorne Hotel, which is located right next to Salem Common in the heart of the City. Lots of good restaurants in Salem as well.
A one day trip to Salem is more than enough. Boston is a city with lots of things to do and see so you should spend as much time as possible in the city and surrounding areas. You can't miss: Fenway Park, Newbury Street, Cambridge, Faneuil Hall Marketplace.
Salem is a great location to visit but its definitely a day-trip venture. You can visit the Salem Witch Museum which provides the historical background of the Salem Witch Hunt. The downtown area is small but has a lot to offer. There are a lot of souvenir shops where you can get magic potions (related to the witch culture here) and even better places to eat. Try Gulu-Gulu Cafe for the best crepes on the North Shore! You can travel down to the wharf area to see old ships. If you really want to stay in town, I would recommend the Hawthorne Hotel. It was featured on the Travel Channel in their program, "Most Haunted Hotels." If you can get past the scare factor, it is a beautiful building. Hope this helps a bit!
Have a wonderful trip! :)
While there is a bunch to do in Salem - it's much more of a day trip - you can take the ferry if you are there in the summer and get a tour of the coastline at the same time. A much better overnight would be Portsmouth, NH or Newport, RI. Cool, affordable inns and great bars, restaurants, sightseeing and shopping.