Sod
With sod you can literally go from dirt to lawn in one day. For many homeowners the payoff is saving the backbreaking effort of seeding, fertilizing, watering, then watching - hoping pests and weeds will not undo all the hard work. You can use your sodded lawn weeks earlier than one that is seeded and it will immediately help control erosion. Another big plus is that you can lay sod during those times of the year when seedlings won't grow quickly.
The best sod should actually contain little soil, allowing the sod to more quickly establish a better root structure. The first few days are critical; sod roots are less than half an inch thick, which can dry out faster than an established lawn. Sod must be watered frequently during the first few weeks, at least once a day, and more often in dry times (July & August).
Mowing should be avoided for the first week or two until the sod is well established. Mow to a height at least 50 percent taller than you will later want. If you want three-inch grass, you will want to initially mow it to 4.5 inches. Remember that taller grass is usually heartier and more drought tolerant than shorter-cropped lawns.