I knew this one was pretty easy, but I have my reasons (below). Gold stars to KB, Jim, John, and Dave for correctly identifying rolls of sod (and they do seem thin, Peter):
Yes, sod. I dislike instant lawns; they never look good for very long, at least in my part of the country. And getting rid of sod (as we have in our landscape) is a nightmare with that *%&$^ plastic mesh in which the grass is embedded. It breaks up into little bits that are constantly coming to the surface.
I don’t have an axe to grind about lawns; my philosophy is that if you want a lawn and can afford to maintain it well, more power to you. But what’s wrong with the old fashioned way of seeding a lawn? Sure, it takes a few more weeks to "grow your own", but seeded lawns look more natural and last much longer.