Taking a guided tour is a good idea, even if you generally prefer flying solo. For one thing, it will help you get your bearings in this sometimes overwhelming city; for another, it's a great way to investigate out-of-the-way areas where you might not venture on your own, or learn about a particular facet of the city's history, inhabitants, or architecture.
In good weather, a Circle Line Cruise around Manhattan island (Pier 83 at W. 42nd St., Midtown West, 212/563-3200, www.circleline42.com) is one of the best ways to get oriented in the city. Once you've finished the three-hour, 35-mi circumnavigation, you'll have a good sense of where things are and what you want to see next. The cruises run at least once daily; the cost is $29.50 per person (there's also a shorter, "semi-Circle" option available for $25).
If you're after a more historical experience, the Shearwater, an 82-foot yacht dating from the 1920s, sails from the North Cove Marina at the World Financial Center (Lower Manhattan, 212/619-0885, www.shearwatersailing.com) and makes two-hour public sails from mid-April through mid-October during the day, at sunset, and for Sunday brunch. Reservations can only be made a maximum of two weeks in advance, and are advised. Fares start at $45.
Gray Line New York (777 8th Ave., between 47th and 48th Sts., Midtown West, 800/669-0051, www.graylinenewyork.com) runs a number of "hop-on, hop-off" double-decker bus tours in various languages, including a downtown Manhattan loop, upper Manhattan loop, a Brooklyn loop, and evening tours of the city. Packages include entrance fees to attractions.
The wisecracking PhD candidates of Big Onion Walking Tours (212/439-1090, www.bigonion.com) lead themed tours such as "Irish New York" and "Jewish Lower East Side," as well as famous multiethnic eating tours and guided walks through every neighborhood from Harlem to the Financial District and Brooklyn. Tours run daily and cost $15; there's a slight additional fee for the eating tours.
The knowledgeable Joyce Gold (212/242-5762, www.nyctours.com) has been conducting neighborhood walking tours since 1976. Her theme walks like "Gangs of New York and the Bloody Five Points," and "Hell Ain't Hot: This Here's Hell's Kitchen," run on weekends and cost $15.
The Municipal Art Society (212/935-3960, 212/439-1049 recorded information, www.mas.org) conducts a series of daily walking tours, which emphasize the architecture and history of particular neighborhoods. The cost is $15 per person.
New York City Cultural Walking Tours (212/979-2388, www.nycwalk.com) have covered such sundry topics as buildings' gargoyles and the Millionaire's Mile of 5th Avenue. Tours are run every Sunday from March to December; private tours can be scheduled throughout the week at $50 per hour with an average length of three hours.
The Urban Park Rangers (866/692-4295, www.nycgovparks.org) conduct free weekend walks and workshops in all the city's parks.