Thats a tough one. We want to be visual as well as just text. Text is king, but nice to have best of both worlds (if possible)

Editors choose "Featured Images" and we really want to allow for the big expressive photos.

Its hard to constrain them and maintain a sane aspect ratio. I'm not disagreeing with you - I don't have a good answer.

These definitely work really well on larger monitors - however laptops, older computers its not the ideal.

Will need to think about this more.

If you want to make it the editor's choice, build a feature that at least gives them visibility into what they're doing. Worst case, just load an article preview in a bunch of fixed-size iframes which match the viewport size of common browsers. Better but more expensive, cobble together a browser farm (getting cheaper now thanks to modern.ie images). Either way, make it a prominent part of the editorial process.

Edit: I think the reason it bugs me is that text is the primary value your site provides. The image is ambiance. Ambiance that blocks me from the value I seek goes from tasteful to gaudy real fast. I get the desire to let editors be expressive, but if you're in a situation where you're forced to prioritize, always prioritize the thing that brought the visitor to your site in the first place. Otherwise you might not have need for the editor at all.