I remember going to the big imax theater in Great America (Theme park in CA). The sound system in that giant auditorium was awesome, probably because the acoustics of the room itself were beautiful. Think of the biggest theater you've been in and that quiet damped delay/reverb you get when you make any sound.
 
I know this is a poor example with all the compression shelving, but it still gives a pretty clear example of the type of "expensive" sounding theater delay/reverb/damped effect I'm looking for (be sure to listen with headphones to hear it):
 
https://www.youtube.com/watch?feature=player_detailpage&list=FLouIIrVTlGTLFIN-Zbcw6zw&v=MOBT-TVAhM4#t=778
 
Listen to the talking especially when the guy sitting down talks. How would you recreate that type of effect? How would you do it using Sonar?
 
<added> I think another example of this type of effect is what it sounds like in a planetarium, though that has a way different timed delay.

A fairly bright room or hall convolution reverb or a non-comvolution reverb algorithm that's close. Then play around with the early reflections, which seem to come in slow and be quite marked, and adjust reverb tail damping to taste. Most of the reverb seems to be in the speech band, so I'd roll off some treble and a bit of low end from the reverb as needed.