By and large, travelers in Vietnam and the other countries of Southeast Asia are seekers of some kind, whether for an exotic location, an unbending of their cultural norm, or to reconnect with their past and come to terms with it. Many prefer to travel in Vietnam alone. For independent travelers, solo journeys are opportunities to make friends and meet locals. Groups of tourists are intimidating, but single travelers -- though better targets for touts and shysters -- also look like they need help ("sympathy touring" a friend of mine calls it) and will likely be pitied (however unfounded) and offered hospitality by kind Vietnamese families.
A certain camaraderie also develops on long bus rides or in the uncertainty and wonder we share with fellow travelers from the West, and a trip that might start out solo often ends in friendships that last a lifetime.
Travel Buddies Singles Travel Club (tel. 800/998-9099; www.travelbuddiesworldwide.com), based in Canada, runs small, intimate, single-friendly group trips and will match you with a roommate free of charge. TravelChums (tel. 212/787-2621; www.travelchums.com) is an Internet-only travel-companion matching service with elements of an online personals-type site, hosted by the respected New York-based Shaw Guides travel service.
Many reputable tour companies offer singles-only trips. Singles Travel International (tel. 877/765-6874; www.singlestravelintl.com) offers singles-only escorted tours to places like London, Alaska, Fiji, and the Greek Islands. Backroads (tel. 800/462-2848; www.backroads.com) offers "Singles + Solos" active-travel trips to destinations worldwide.
For more information, check out Eleanor Berman's classic Traveling Solo: Advice and Ideas for More Than 250 Great Vacations, 5th Edition (Globe Pequot), updated in 2005.