Something I learned recently from tempo and mimimari that might help make it more palatable is to make bone broth in two stages. In the first stage, I just add bones and water with a bit of vinegar to help extract the minerals, and cook up the broth as a base. In the second stage, I transfer the broth to another pot, add pieces of bacon, fatty meat*, ham hock, onions, garlic and collard greens**. I add more water to bring the level up, add some more vinegar, and boil again into a stew. When I dish it into a bowl, I add salt and vinegar to taste. The bacon and ham hock help a lot with the flavor, but the integrity of the initial batch of bone broth is preserved by cooking it separately.
* I've found that the local store where I buy pork (my local free-range vendor does beef and lamb but not pork) often has fat trimmings if I just ask at the counter -- they sell at the same price as soup bones, so it's a fairly inexpensive way to get good fatty meat.
** The collard greens (or sometimes kale) is a trade-off -- I'm wary of the anti-nutrients, but it gives some added flavor that makes it more palatable to my daughter, who has generally disliked plain bone broth in the past, even with salt; she asks for it a couple times a day when I do it this way, which is why I'm using it for now.
