After many patterns, as well as tweaks and resizing of those patterns, I've decided on some finial patterns for the Vienna. I may still tweak these slightly, but I'm more or less settled on these.
The top finials I'm very happy with. I went through 3 patterns in various sizes, and these seem very nicely balanced. It's important that they not be too wide or too thin.
For the bottom finial pair, they did not look good much wider than this, because the holes for them are SO close to the bottom bracket (about half an inch). The thinness continues the lines of the door columns.
I may tweak the bottom finial more, but the size and general shape work.
All these patterns are simply 4x6 index card, cut on a centre fold, and quickly painted with black acrylic paint.
Next, I'll have to prepare my blanks.