Kaitoke Beach, New Zealand

For novice solo travelers who'd prefer to visit an English-speaking country but are still looking for a far-flung adventure, consider New Zealand and its trove of wide-open spaces -- including Kaitoke Beach on Great Barrier Island. (Kenny Rodger / Associated Press)

Whether by necessity or choice, a quarter of Americans take at least one vacation by themselves each year. Some solo travelers are single. Some have partners who dislike travel or have different interests or can't get away. Some just crave freedom.

But all face the same question: What's the best trip for the person traveling alone?

"The key is to know yourself," said Beth Whitman, author of a guide for women traveling alone and founder of Wanderlustandlipstick.com, a website devoted to advice and tours for women on the go. "There are times when you just need to get away, to recuperate. And then there are times when you want to be with a group.

"If you just had a breakup, you don't want to run off to Paris because everyone is kissing."

But unless you're a misanthrope, you'll probably want to socialize a bit. With that in mind, here are 10 vacation suggestions for solos. The ideas are gleaned from experts and based on my own experiences.

1. Special interest tours: Whether it's a cooking class in France, a camping trip in the Rocky Mountains or a gay cruise, you'll make friends faster when you have common interests and inclinations. These days, you'll find group tours for seemingly every niche. A good travel agent can point you to the right one.

To see what's out there, check the United States Tour Operators Assn. (www.ustoa.com), where you can call up operators by interest and trip type. The National Tour Assn. also offers a search at http://www.ntaonline.com/livelife. But beware of the single supplement, an often-hefty surcharge for solo travelers.

Another good source can be nonprofit groups, such as the Sierra Club and ski clubs, that organize trips for members.

2. Volunteer vacations: Do good, see new places and meet other humanitarians.

About two-thirds of volunteers with Habitat for Humanity International (www.habitat.org) sign up solo, said David Minich, its director of global volunteer engagement. The nonprofit, ecumenical Christian ministry, based in Georgia, builds affordable housing around the world.

Most Habitat trips, which cost about $100 to $150 a person a day, plus airfare, are priced for double occupancy, but trip leaders can match you with a roommate, Minich said. You usually work five days a week, with weekends free.

Among the many online sources for other volunteer vacations are Volunteermatch.org and Globalvolunteers.org.

3. Bed-and-breakfast inns: Handy for socializing and getting travel tips.

"You're often forced to chat with one another because you're sitting around the same breakfast table," Whitman said. "You meet the proprietors and get the inside scoop on what's in the area."

4. Hostels: These budget lodgings, known for dorm-type accommodations, are not just for young people. You typically pay per-person rates (except for private rooms, which many hostels also offer), and you can meet travelers from around the globe.

Hostel life isn't for everyone. You'll likely share a bath whose cleanliness depends on your fellow guests. Some hostels aren't in the best or most convenient part of town.

Whitman thinks hostel folks are friendlier and that "the higher-end the hotel, the fewer people you're going to meet." From my own travels, I can vouch for that.

The nonprofit Hostelling International (www.hihostels.com), the best-known name in this field, lists thousands of places in scores of countries.

5. Rail trips: The beauty here is that you can keep to yourself, reading or staring at the scenery for hours, or socialize in a view car or dining car. Fares often match or beat airfares.