stock photos... would be, by myself at least, unwelcome.

Not just you; by myself too at least. Besides the... glibness of it, It's also annoying to spend even a few brain cycles on figuring out what an image has to do with a story, and then realize it's just stock. (As someone had pointed out on /. critiquing the Beta, an actual image seems to imply it's something specific.)

OTOH well-chosen specific images work well - for example, the earlier story about the "world's coolest new watch" looks great.

But icons are fine too - they're understood as thematic (i.e. stock), but may also aid in navigation. (E.g. when scrolling rapidly, looking for a story you saw earlier.)