Mark -
I've enjoyed the articlese I've read thus far, which I think were the first 3 on your list. Thank you very much for choosing a Merion hole for your short par 4 - it would have been more obvious to choose something like Riviera's 10th, but I'm happy to learn more about Merion.
I'll have to think about it some more, but off the top of my head, I'd like to see an article challenging some of the conventional wisdom of golf - i.e. adding length to combat length, narrowing the fairways & growing the rough to promote accuracy, flattening greens so you can increase the speed, because stimping 14 is tougher than 10 regardless of contours, etc. This might even be too much for one article, it might have to be a series.
I played Inniscrone (in Philly) and Lehigh on back to back days. I shot low 90s at Inniscrone and low 100s at Lehigh, yet I lost a couple tee shots and incurred some penalties at Inniscrone, while I didn't lose a ball at Lehigh. Most people still don't understand what "defending par at the greens" truly means.
I think an article about why subtle courses will always be underrated might provide some insight as to the foundations of gca. There were recently some posts on here about how the interplay of tee shots, approach shots and green contours all relate, which is in direct contrast to the current en vogue notion of independent shot values and course rankings. You can use Hidden Creek as the poster child for this phenomenon.
I also think it might be worth doing an article on your First Tee practice facility.