I grew up in Saugus, which is just a few miles from Salem. You are going to LOVE it! There is so much to. Please be sure to check out fun places like the Witch Museum, The Fools Mansion (It's a costume shop, but fun to play around in), and The Salem Willows (2 arcades, state park, and beach right on the water).
I would recommend the Peabody Marriot. If you stay in Peabody, Danvers, or Beverly, then you should be fine. Homestead Suites in Peabody is $100.00 per night.