Thanks for the info on soaking the bones first. I do really good with chicken bone broth, but not so god with beef. Have you ever tried adding a few chicken feet? I find they add a lot of collagen to the broth.
Yes, I have done chicken feet (and heads, and necks). They do add a lot of gelatin. I generally stick with beef broth simply because it is almost tasteless, yet seems to bring out the flavor in just about everything. By contrast, the chicken-based broths tend to dominate in flavor (sometimes, not in a good way!).