So, the question is, how many dollars must my time be worth before the cab option is the most optimal? Assume that there is some factor X which converts minutes to dollars. The public transit and cab options are "equal" in total cost to me when this equation is satisfied:
1.40 + 1.25 + (40 * X) = 9.00 + (15 * X)
which happens when X is 0.25 dollars-per-minute, or $15.24 per hour.
Similarly, comparing the cab vs. walking:
30 * X = 9.00 + (15 * X)
suggests that the cab is a better option if my time is worth at least $36 per hour.
The upshot is that I think I'll never take the bus again. :) The exercise (in non-rainy weather) has tangible benefits to me, but I'm pretty sure my time is worth more than $15/hour. Or would be, if I weren't salaried - this is sort of academic at this point.
Having figured this out while wandering down Valencia, I finally found a cab. He called in the pickup as Army Street - I wonder how long he's been driving a cab, if he still thinks of it as Army? - and in fact made better time than ten minutes. Sweet.