I think you're wise to recognize that there's not much to be gained by forcing anyone to do anything they're not really into. (In fact, is it even an option for husband to stay at home? I don't want to assume that "combat vet" automatically equals PTSD, but there's a lot about the WDW experience that could be challenging.) But there's also the fact that even somebody who's not
that "into it" gets sucked in by the experience and has fun after all. Our 13yo daughter was all "I don't even care about WDW, I just want to do HP" before our trip, but wound up enthusiastic. Give your 12yo room to change her mind at the last minute and opt in if she wants to.
The parks are, by their nature, a "sensory overload" experience. Aside from the intensity of rides, there are crowds, noises, pushing and pulling; there are even scents and music piped in to make sure you don't have an un-stimulated moment. The
Genie+/ILL/VQ systems have us on edge, feeling that we must fight competitively, and that if we relax and take our time we're leaving money and/or "fun" on the table. It sounds like your husband might enjoy some of the places that are oases from the stimuli. It's basically all the things that nobody tries to elbow their way into because they're not as exciting. Some of those, for me, off the top of my head:
- Tom Sawyer Island
- Tomorrowland People Mover
- Carousel of Progress and Hall of Presidents (though that might be a little too zen?)
- Epcot World Showcase in general, especially the garden areas of China and Japan
- Lots of corners of AK like the animal trails
And in general, many sit-down meals can provide a nice respite. Jiko was dim, tranquil, and an amazing meal. Sometimes the right table makes all the difference; the "butterfly booth" in Skipper's Canteen is awesome.
For folks who don't like rope drop...
and don't like crowds...
and prefer to be unplanned... sometimes evenings can be great times. If you get Extended Evening Hours, go for them; maybe consider buying an After Hours event? You get everything husband and 14-yo are looking for: relatively empty parks, do stuff in whatever order you want, and you can wake up at 7pm

.