Some more updates; the factory Bose speakers sounded OK-ish after 17 years of use, but at least one was fully blown and they were all a bit muddy. I picked up some cheap speakers to throw in place and they definitely made a big improvement for a low cost. Not audiophile or show quality, but they work great for me.
Old BOSE speakers, well worn
New replacement speakers - 5.25 for the rear, 6.5 for the front (I think)
Besides fighting fragile plastic clips inside the door panels, it was a super easy job. The rear speakers screwed in place with the factory holes and hardware. The front required a bracket that Crutchfield sent me for free - and the screws included with the speakers worked fine. Crutchfield also sent along some adapter harnesses so I didnt have to cut the factory in door wiring.
I also grabbed a junkyard RSE control unit with HVAC controls to replace my well worn and only partially functional one. Super easy swap - pry the old one out gently with a flathead screwdriver, unplug it, plug the new one in and push it into the open hole. I need to deep clean my new junkyard unit but the kids are wicked happy they can control their temperature now.
And, of course, there are always the fun things you find when disassembling older used vehicles. In this case, coloring book pages and gum wrappers.