In general I don't think it's a good idea to try and use reverb to make something clear, i.e. if it's sounding dull to you, then eq it first. If it were a low drum in a pop mix, then sure, you tailor the reverb to the sound more. But in this case you're trying to create a realistic space.
Having said that, some of the Altiverb impulses are wider and clearer than others. I forget the name of the small church I really like, but if you shorten it, it works really well for orchestra.
The other thing is to make sure the timing is right. When they're doubling hits, timps (like bd) usually play at the front of the beat, even though they're at the back of the stage. If you quantize the timps, they may be too late.
And of course you want to boost the velocity all the way.
Dietz? Help!
(This should probably be in the mixing area, actually.)