Decisions, decisions

You would think that something as simple as a garter stitch scarf would be quite straightforward, but it seems I'm capable of turning it into nothing less than a series of major decisions. Major, because this scarf is for James' birthday and I want to get it RIGHT.
First, since he wants a striped scarf, we have to decide on the colours. He wants black and something else. So I hunt through my stash and we discuss the options. Black and red (Trinity College colours)? The red is too bright for his taste. Black and grey? Too boring, I say. Black, olive, and grey? Better. Black, olive, and navy? Yes.

Cascade 220 in black, navy, and olive heather

 Second, I have to decide on horizontal or vertical construction. I like the look of the latter, but the problem is that I will  have to decide in advance exactly how long the scarf will be. Also, the cast-on may involve hundreds of stitches. Undaunted, I decide to forge ahead with a lengthwise project.
Third, I have a discussion with James about the exact dimensions of his birthday scarf. He shows me the ratty synthetic one he is currently sporting (how embarrassing for his mother, the knitter!) and tells me that he wants the new one to be both longer and wider. How long? 72 inches. That's how long it will need to be to extend to his fingertips when he wears it hanging around his neck. He wants to have enough for wrapping.
Fourth, I need to decide what gauge I will knit at. The Cascade 220 I'm using knits up at 4 1/2 or 5 sts per inch. I think I will knit at the looser gauge, since that will help the scarf feel softer and drape better. I work out that 72 x 4.5 = 324. YIKES! That's at lot of stitches. I reason that the scarf may grow a little when blocked, so I nip 2 inches off and arrive at a cast-on of 315 stitches.
Fifth, I need to decide what type of cast on to employ. Long-tail cast on will give lots of elasticity, but it won't match the cast off. I want the two sides of the scarf to look alike. So, I steel myself and cast on all 315 stitches using Sally Melville's crochet cast on from this book. It's slow and tedious, but well worth it. See?

Crochet cast on on the left.