It might be worthwhile to note:

If you are in a position where you need to see the AOE range (to avoid hitting something you don't want to hit), you should probably avoid AOE all together ^.^;

The range might be fine when you start casting, but thanks to mob movements, popping, and lag, that may change by the time it hits.

So far, as a WHM/BLM and THM who solos a lot, I've never ever been put into a position where I needed to worry about AOE range. If I was worried, I would use a non-AOE skill (plenty of those).

Yes, there may be a specific situation:
If I knew the exact range I could use Fira and increase my damage to this fire-weak mob rather than use Thunder, but I'm concerned that other Goat that is 1 yalm away might get hit and then beat me up.

If this is the case, you could:

-- Go fight something else that has nothing in range or is weak to thunder
-- Pull the mob away from other creatures to a safe point and then use Fira
-- Keep using thunder till the big Goat wanders off then use Fira


Lots of options ^.^b