Here are a few items for the list that have rattled around in my head for a few years, all "enhancements" to existing capability. These are all based on v14, which is the latest I have.
1. Areas; while not in inital relaese of Prime, I find the current behavior lacking in the ability to place the end of an area far below the beginning. Unless there's a way I don't know about, repeatedly dragging the end and scrolling the screen down is a drag in both senses of the word. It would be useful to have independent means to place the start of an area and the end of an area, especially if the end is many screens/pages below the start.
2. Find/replace: I expect to be able to search or replace anything that is in fact valid math, e.g., column operators, subscripts, math definition operator (:=), etc. Now, the search (and replace) fields are limited to text. The copy and paste should work with a valid math expression into the search field, especially when looking in math areas.
3. User-defined functions with a) means to have optional arguments like the built-in rounding function, and b) means to indicate an argument list not necessarily pre-defined in length, e.g., like the built-in max function.