Thanks for the discussion.
So I actually have two areas; the 20x20 front yard patch (basically the badly sloped area) that I want to turn into a wild-flower patch. I tried last year without nuking the grass and it didn't work.
And then a smaller backyard plot for a garden with herbs and a few veggies, sunflowers, etc...
It sounds like the roundup approach will work for me, for favoring that, for now. Am I going to have to tarp the grass after putting down roundup if it rains? (suppose to be a decent amount of rain here in E IA this weekend)