I never considered Combat Awareness... that's fairly neat as well, though limited. Building a character around a 1/day weak ability isn't quite so useful. Although I suppose Combat Awareness does have other decent uses.
I'm thinking the "reliable" tag is probably my favorite solution; Both caster level and effective turning level are far too easy to boost. And in the case of a prestige class that requires access to the Death domain, I'd allow that to stack - most of those are rather uninspiring, like True Necromancer. I think the easiest way would be either give multiple uses - 1 extra use per 5 levels, perhaps? - or go with the Reliable idea. Which is better, do you think?