My bone broth was sort of bland until I started adding turkey necks and that made a huge difference. Also added beef tendons and they are quite tasty themselves after simmering for a few days.
I usually keep my crock pot going for 2 weeks or so. Sometimes I will add some vegetable and leave it for a few hours and then dip them out and eat them.
Bone broth is not only very nourishing, it is lots of fun to tinker with.