The text block was an easy fix, and now has a good, tight bind. I layered some book tape over the glue to reinforce it and allow it to lie open without cracking the spine. The cover was trickier… I actually got really ambitious once I realized that the shoulder was torn most of the way up the spine, and that the covers were merely dangling together. I rebuilt the cover entirely.
The catch to doing this was to soak the old covers in warm water for 20 minutes or so before trying to remove them from the front and back boards. It took some trial and error, but it came off pretty well in the end. I learned that the key to this step is patience. I tried rushing the process, and it just made more work. Let the cover soak, then peel it off.
The one thing I wish I had done differently involved the spine. I decided to put a full strip of board on it instead of just a sliver of index card stock, so the book feels wrong when you hold it. There is no flexibility in the spine when you open the book. It has definitely given the book a solid construction, but it isn't done right.
A second imperfection is on the back cover. Once I built the new covers, I glued the old picture cover onto them. I was rushing again, and didn't get the back cover aligned very well. Still, I'm pleased with the outcome. I managed to save my book, and I learned a lot that I can use in future repairs. I also feel a lot more comfortable daring to attempt a more involved repair.