I have an altiverb on every instrument with just the early reflections on and then I have a tail on a Aux track that they all send to. For the early reflections I use Toldex and for the tail I use a VSS3 from the TC Powercore.
I do this so I get the sound of the instruments in their position in the room and then add the tail using the reverb that alot of the studio's use to add to orchestras for film. To my ears it sounds pretty good, it does mean that you are running alot of altiverbs but my computer seems to cope fine.