A brief epilogue to this story...
As I suspected, several hours of reminiscing about the photos on day one. Since my brother-in-law is a dozen years older than my wife, there were plenty of things he knew that my wife didn't. Yet, there were stories of things told to my wife that my BIL didn't know about.
About 300 images were scanned, I think. The tag-team process worked very well. Image resolution was adjusted as we went. I spot-checked as we went along, but real image manipulation on 14" laptop screens (when used to doing stuff like this on 27" dual monitors) just wasn't going to happen there.
One of their uncles had also shot some old slides back in the early 1970's; I'd never seen them this small. I did scan a few of these. I had a single uncle (on mom's side of the family) that shot slide film back in the 60's and 70's. It took a bit of effort to figure out how to scan them, but trial and error worked.
I think there's about a dozen images that will really be worth the restoration efforts - once I get a better understanding of Lightroom.
In the next week or so, I'll post up a couple of them to share the results.