[notfarnow]

I went through this last spring. There is a great older thread here on PP that had tons of info, it was very helpful for me... I'll see if I can find it.

FWIW, my understanding is that a good layer of topsoil is what makes the difference between a healthy, thick lawn and one that dies off or turns to weeds in a few years. Most places say 4"-6" of good topsoil. It's also very helpful if you can get recommendations for good clean topsoil, as above.

I had 2 weeks off last spring, so I put down grass seed. I don't have a sprinkler so I had to water it 2-3 times a day to keep it moist. It turned out nicely, but it was slow going. Easily a month before I could walk on it. Sod is great because it is so fast. Looks great right away, but again, make sure you have a good layer of topsoil so it stays healthy.

Hydroseed is a good "in between" option. Cheaper than sod, but still very fast. I'll be going that route this spring.