[Silound]

Personally, I wouldn't use a weed'n'feed at all. Almost all of them target a specific type of weed but don't do much to stop anything else.

I would start with a base coating of RoundUp twice a week for two weeks, and till the land to a depth of three inches in between weeks. One week after the last spraying, I would seed the ground and water it well. As soon as the grass starts to sprout, keep a close eye for weeds and unwanted clover and other things sprouting. After the grass has a good footing I would come back and spot spray it with Crossbow/2,4-D to eliminate any unwanted broad-leaf weeds growing. Fertilize as recommended by the seeding instructions after the spraying.

That's what I would do...a bit more expensive but cheaper than sod and helps prevent overgrowth of unwanted crap.