It's done! My new drapes and valance are up and doing their thing! :-)
No, it's far from perfect. I had to re-learn the measure twice, cut once rule. For instance, when cutting the long piece for the 12 foot valance, I very carefully measured 8 feet and made my cut. OMG!
But, waste not, want not. I centered the 8 foot valance on the 12 foot shelf. The drapes which hang from each side cover the bare spot. However, they can not be tied off down the side, because then the exposed edge of the valance piece shows. However, I don't care. They can lie nice and flat and still look pretty good. MUCH better than bare corners. And they hide the blinds in the corner when they're open.
A few teddy bears now sit atop the shelf surveying the living room. Soon they will be joined by some cast iron trains, which I have, and some "antique" canned goods, which I'll start looking for in antique stores. (Don't worry, the shelf is screwed to brackets and won't fall.)
The sticky tape no-sew hem thing worked like a charm. Made it pretty easy.
And last, but not least, the project came out looking very much good enough for my needs, but not so perfect that a woman who sees it won't conclude that I'm too self-sufficient. Likely, she'll conclude that I have my heart in the right place, which is a good thing, but -- I could use a woman's touch to make it just a little better! So, it's a win-win all around!
Gary