i suggest making an easily scalable (for different resolutions) MQ ui. I swore by the drakah ui for a long time, but am finding the sars a lot cleaner with a lot more viewable space.
check it out:
http://sars.has.it/
it'd be really nice perhaps you could use the nice lookout and feel of this ui as a base (and of course, give credit where it is due to sars) and add some spunk with information.
I would suggest an "MQ enchanced" target window to add npc level, and perhaps on the caster veresion put some flags for whether it's charmable, mezzable, etc. I'm not sure if that information is available, but if not, keep the clutter down... NPC class / race rarely matters.
Also, an addition to the player window including some zone information (like a display of the exp bonus in the current zone, based off the $zone(zem) values).
But really, as much information as EQ provides, not quite much more than is already on UIs is extra useful. But those are the 2 things I would think would be most helpful and convienient wihtout cluttering up the place.