I have both of those lenses. They have produced a lot of photos that I am happy with. My complaint about the 28-70 is that it is not very wide, especially if you have a crop factor. The 70-300 is a bit soft on the edges, but it can work for you if you know about it. The center is prettty sharp for a $100 lens. I actually am finding it easier to get decent results from than my Tokina 400 /5.6 ATX. Then again I am still getting used to it.
I'm sure you got all that and more from reviews, but I figured I would put in my opinion anyway.