Seeking Landscaping input

I am considering planting a large yellow ribbon on a hill in front of our house this spring. I'm looking for some input on the following questions:

What type of plants should I look at planting? I certainly want something that will give a yellow color (since the goal is a yellow ribbon). Ideally, I would like something that will provide color for a significant part of the summer. I'm willing to plant two different types with different bloom periods if needed. The soil condition on the hill isn't the greatest, so fickle plants might not do well. The plants will also experience evening shade since they'll be on an easterly facing slope. Worst case, I've considered planting dandelions, but I'm not sure they'll give a consistent enough bloom to give a good ribbon shape.

Is there a green colored landscaping fabric available? I would like to get a heavier grade landscape fabric if possible. I know there is a "commercial" grade that is 2.8 oz vs the 1.3 oz typically sold for home gardening use, but I've only seen the heavier grade in black. I've considered putting down the heavier grade black fabric, then a green colored light grade over it, but I'm concerned that the layering of fabrics may impede water/air flow to the soil and kill the flowers I want instead of just the weeds that I don't want.

Any input and suggestions would be greatly appreciated.