Portland's location on the southern Maine coast puts several worthwhile destinations within easy reach.
Bath is about 45 minutes northeast — a town of fewer than 10,000 along the Kennebec River, known for shipbuilding heritage and fine examples of Greek Revival, Federal, and Italianate architecture. The Maine Maritime Museum on the riverside is well worth two hours.
Freeport, twenty minutes north, exists more or less for the L.L. Bean flagship store — open 24 hours — and the outlet shopping that has grown up around it.
Boston is only about 110 miles southwest, reachable in just over two hours by the Amtrak Downeaster. Despite being two states away, it is a practical day trip for big-city museums, historical sites, and restaurants.
White Mountain National Forest covers nearly 785,000 acres across New Hampshire and into Maine. Bartlett, New Hampshire, in the middle of the forest, is about 90 minutes northwest of Portland — a good base for hiking or skiing depending on the season.
Acadia National Park is a three-hour drive northeast. Doable as a long day, but better as a weekend trip — Maine's only national park and one of the most-visited in the country.