Would probably need to be implemented on a per-plugin basis but the ability to choose whether plugins display as just text, just icons, or both (possibly with text below/besides option for different panel widths) would be appreciated. You can already do this with the xfce4-places-plugin and you used to be able to do this with the old tasklist plugin (pre-4.6 libwnk-rewrite) but few other plugins provide such an option. If nothing else, not being able to turn off icons on menu plugins and the tasklist makes things a little cluttered.