I'm developing a host based on the demo host example. One thing that I'd really like to do would be able to have a generic editor that allowed textual input of non-normalized parameter values, and display of enumerated lists and boolean parameters using appropriate UI elements (e.g. drop downs and check boxes), rather than a slider for each parameter. I think this should be achieveable for VST3 and also AudioUnits.
Also it would be nice to be able to access information about parameter grouping (VST3 UnitInfo / AudioUnit Clumps).
If you're listening Jules, it would be great to have these aspects exposed in a generic way.