a·ston·ish (ə-stŏn'ĭsh)
tr.v., -ished, -ish·ing, -ish·es.
To fill with sudden wonder or amazement. Synonyms: amaze, astound, awe, startle, surprise.
[Alteration of Middle English astonen, from Old French estoner, from Vulgar Latin *extonāre : Latin ex-, ex- + Latin tonāre, to thunder.]
I can't believe the response the vest got - thank you so much for the lovely comments. I'm working on putting the pattern together, and will try to have it up by or over the weekend...it will, unfortunately, cost a little bit - $5 or $6 - but I promise you'll get what you pay for: full-garment charts for every size, detailed steeking and blocking information, and diagrams galore.
Guts!
By popular request, the inside of the vest:

The pattern reads a lot better on the inside, which says to me that I should have switched colors in my right and left hands.
And the finishing on the turned-down steeks - I just blanket-stitched them with another strand of the Tiur, all the better to help them eventually felt.

Developing the pattern
What I think of as traditional Argyle looks something like this:

alternating blocks of two sharply contrasting colors on a medium-toned background. The effect is of two contrasting, sheer ribbons woven together. I really like this look, but prefer something more graphic, with a bit more punch. The logical step, then, is a wholly two-color pattern, with the blocks arranged in a checkerboard, and the lines done in an opposing checkerboard:

I love sweaters patterned this way, but don't love the intarsia involved - instant-gratification monkey that I am, I wanted to knit the pattern using the (already quick) circular stranded Fair Isle method so I could steek (even quicker). I had a certain width to each block in mind, but wasn't comfortable with how long it would make my floats over the widest portion of each diamond shape - so I added another line of contrasting color in each block to pare the longest floats down to 5 stitches:

Why does it matter? I guess it doesn't, really, except that I like the the knitted qualities of a pattern with frequent color changes - it becomes a cushy, firm, still-drapey fabric. I know very long floats are not uncommon, but I just don't care for them - I think it makes for a messy garment, with stitches easily distorted during wear and none of the structure that properly belongs to a Fair Isle jumper.
Charting did take a while, since I was too knuckleheaded to figure out some fairly obvious math issues. Did you guys know that even and odd are different? I felt brilliant when I finally figured out 12 stitches would split in two identical groups, but that 13 wouldn't...um, yeah.
**Please note that I'm in no way suggesting that I'm the first to come up with this variant on argyle - I'm sure it's been done many, many times before**
Anyway, the final product is more or less exactly what I pictured - a very fitted, snappy little sweater vest. It's also a little bit of a sartorial wink: Western Scotland's tartan knitted with Shetland's method; old-school patterns filling a modern outline; a traditionally laborious-to-produce look done at today's right-away speed. I like it a lot.
Right Now
As a little break before I start the knitting on my next big project (so excited about this one, though I think it'll take a while to get just right - it'll give me a chance to get out some of my knotwork cable ideas), I'm working on Knitty's Shedir hat:

I detest Calmer with the fiery heat of a thousand suns, so I'm using Rowan Felted Tweed, instead. The yarn doesn't have great stitch definition (it's rather loosely twisted, and it's, you know, felted and tweedy in places), so I'm doing all those pretty cables with a twisted stitch instead of a plain knit stitch. I normally don't care for interesting yarns and texture together, but I think the overall effect of this'll be subtle and sort-of sophisticated.