rory.c: For the big one, I used the latest PrusaControl slicer. For the small one in vase mode, I tried Simplify3D. As you can see, your concerns about handling the angles near the top are well founded.
If time permits I may crop the top off in such a way as too leave the face in the front but lower the back to use as a candy bowel. At 87% scale, it could be a bit bigger since the Z dimension is currently maxing out first.
Since my plan was to light it from the bottom with a tealight, those little gaps aren't too bad.
I did a small one with PrusaControl and light it and the effect is great, but I would need to use a more powerful light source.
JeffJordan: I use a few brands of PLA and for most the default flow is fine. While the base was being laid down, I noticed it was a little under extruded so I bumped it up a little. I spot checked the filament in a few places and its a hair shy of 1.75mm in most places. For $15 a Kg, its still a great value.