Known for walkable urban villages like Crystal City, Rosslyn and Ballston, Arlington was part of the "10 miles square" surveyed in 1791 to be the United States capital. Just across the Potomac from Washington, Arlington is home to the Pentagon, Arlington National Cemetery, the Marine Corps War Memorial (Iwo Jima), Air Force Memorial and Pentagon Memorial. With 11 Metro stops, Arlington is car-optional and offers visitors everything from eclectic theatre to Bohemian cafes.

Home to two of America's most prestigious universities, Cambridge exudes a certain intellectual quirkiness. A mix of historical haunts, student hang-outs, alternative art and culture venues, vintage clothing shops, bookstores and ethnic restaurants, the city is, well, really cool. Although it is located just across the Charles River from Boston, Cambridge has a distinct vibe that is noticeable immediately. Start at Harvard Square, a hub of activity and mishmash of trendy stores, outdoor cafes and colorful local characters. Pick up a walking tour map at the visitors information booth in the centre of the Square. The route will take you past many important landmarks including the Mount Auburn Cemetery, Tory Row and the Longfellow National Historic Site. Harvard University offers student-led tours through the illustrious buildings and monuments of its sprawling campus. Art and architecture buffs should meander around the M.I.T campus, which includes outdoor sculptures by masters such as Picasso and 20th-century buildings designed by modern greats like Eero Saarinen and I. M. Pei. Along the way, browse through bookstores, stop to watch street performers and grab a coffee at an outdoor café to take in all this captivating city has to offer.

Romance and adventure are in the air on this lush West Indian island in the Caribbean, depending on your coast. To the west, you'll find calm waters and good swimming. To the east, there are massive, competition-caliber waves. Wherever you stay, expect turquoise waters, fine soft sand beaches, catamaran cruises and delicious island fare.

You can easily fill a week with activities in and around the mountain village of Boquete. Tours of every sort—jungle tours, coffee estate tours, hiking tours. Adventures for every age—ATVs, zip lines, white water rafting. Or just relax and let your travelling companions do all the adventuring. Boquete's good for taking it easy, too.

Make sure to pack your wellies, because Snowdonia National Park is one of the wettest spots in the U.K. Besides being soggy, it’s also pretty impressive. A fairly easy hike takes you to the top of Yr Wyddfa, the highest peak in Wales (topping any peaks in England, too), where peregrine falcons nest in the jagged cliffs. The park also has the largest lake in Wales, Llyn Tegid. It has its own Loch Ness-style monster—called Teggie, of course—though some figure it’s just an unusually large pike. This Snowdonia’s wonders can also be found on a smaller scale. Keep an eye out for the Snowdon beetle, which has rainbow stripes down its back.

Bask on four miles of golden beaches, hit the Mediterranean Sea on water skis or stroll along Benidorm's promenade and revel in its seaside charms; it's a true Spanish beauty of the Costa Blanca. Originally a fishing town, the city's historic center wows with its blue-domed 18th-century church and picturesque alleyways. Panoramic views reward those who climb into the surrounding Canfali hills, and nearby rocky coves reveal underwater riches for scuba enthusiasts. End a day in the sun with a feast of local seafood.

Sunbathing, al fresco dining and late-night discos are a way of life in Hammamet, the Tunisian St-Tropez. Located on the fertile Cap Bon Peninsula, about 40 miles south of Tunis, the bayfront resort is surrounded by verdant hills and citrus groves. When not basking on Hammamet Beach, browse the markets for local pottery or wander through the medina (old city) with walls that date to 1500. Summer brings festival fever to the city with plenty of music and theatrical offerings.