I was wondering if somebody could help with this mind puzzle. If you were a watcher of a show called Gargoyles, you might remember that Goliath would fold his wings over his chest to form a cape. I would like to achieve that with my rig, but I’m not sure how to go about doing it. I have rigged the arms of the wings using bones with StretchTo constraint and the fingers using SplineIK constraint. The area in between is where things do not look right when deformed.
Any thoughts on how to approach that part? 
Hey ! I watched that show ! great !
What you’re trying to achieve is quite complicated. You can probably come up with an ultra fancy setup that allow you to have both the wings and the cape with the same controllers / geometry…
Chances are that it will be very hard to pull of, it will also be easy to break and hard to animate with… (yes I’m an optimistic guy …)
The simplest way to do this kind of things is to have two sets of bones and two meshs, one for the wings and one for the cape. You then have a value in the rig that allow to show one or the other.
(like IK/FK switch) .
depending on the style of animation you can switch from one to the other in one frame.
you start with the wings and let them start forming the cape , you then switch to the cape in the next frame, and put the cape in a position similar to the wings in the frame before.
The fastest the transition is the best result you will get.
Things can start to be a bit more complicated if you have motion blur : that will probably fail during the transition. Same thing if you plan to have a slow animation for the transition but it’s better to try to avoid that and move forward to more interesting things in life 
If you really neeeeeeed that , probably it would be better to think it like the IK-FK switch : same geometry but deforming bones goes from one set of bones to the other, still it’s a lot of planning to get it right …