Here are some observations from our spray painting session. We painted both the Natural and Sandblasted Manzanita. The Sandblasted sops up the paint fast, and would be the best choice for a matte finish (such as if you are making "coral"). Also, as it is light in color, you'll likely need less paint to get the color you want.
The smooth bark on the Natural Manzanita keeps the paint from penetrating the branch and is what you'd want if you're going for a glossy look. We didn't prime the branch, but we probably should have as quite a few coats was necessary to get the color we were going for.
Lastly, may try using a paintbrush next time - with spray paint, more paint ends up missing the branch than hitting it (we may just use the paint brush to mop up the puddle of paint underneath the branch).