I couldn't help but make an animation:

I hope it can be helpful for your project.
I didn't animate the hat on purpose.
That looks pretty awesome

It'll make a great reference to look at when I make an idle animation, I really like how the hair moves.
Myeah, this larger witch is much more work, but indeed all those extra yummy pixels to work with.

Important things:
She looked like she was leaning back, so I changed that. (Does she have a name, btw?)
I saw the opportunity to make her hand bigger to give her more character!
Extra space inside the crystal ball means you can put little cues as to which spell is currently selected (here is what I imagine teleport would look like) without adding much extra work or confusion.
I only just thought of this now, but that also means you can probably add a staff quite easily.
Unimportant stuff:
This is how I had imagined her clothing looked when she was smaller.
Keep up the good work!
EDIT:
Almost forgot to mention - those faces are frikken awesome! So much emotion, I love it.
Yeah, it'll definitely be a bit more work, but I think the upsides make it worth the effort. It's a good chance for me to improve too.

Anyway, you fixed a bunch of issues I was having! I couldn't find a good way to get the part on her shoulders to look right, that's why I tried the bandanna as an alternative, though the green felt a bit out of place and I had been trying to find another solution. I went back over the sprites based on your changes and ended up with this:

The first is the original for comparison, the second and third are the new ones, but the second has a small change to the legs/feet that I was trying out. I also tried out a new version of the orb with your idea of having the symbol inside of it, it seems like it could work pretty well along with color changes for the orb.
Glad to hear that you liked the emotions by the way!

Speaking of which, as soon as I finished them and looked them over the name Cynthia popped into my head so I've just been going with that for now.