Applications like Yakuake shouldn't be tiled, but always be in floating mode (forcedFloating = true). There should be a configuration file where a list of those applicatios can be found. It should include a sane preselection.
The user should be able to simply add or remove appliclations there. It might also be convinient to add a GUI menu entry for this (shown in the Alt+F3 menu, maybe Tiling > always float application)