A big UI improvement for me would be to fix the Standard / Advanced / Post / Pricing field panels to the right side of the screen so they're always visible/accessible when working on a long form. As-is, I do a lot of scrolling down then back up to add/edit fields; if those panels could be position: fixed instead of just at the top of whatever form I'm working on it would be a huge help.
This is a function I've added to my theme to make that happen, but it'd be great if it were an option or just the default for the plugin: