Applying Reverb on the whole mix.

I am currently mixing on a project that was recorded live with about 80,000 people in attendance. Many telescopic mics were used to record the ambience. As a result I have many pieces of small groups of people and am having trouble getting that larger than life "huge event" like sound. I'm also dealing with the fact that the event was completely outdoors and the ambience itself is rather dry and lifeless without interesting reflections. Although I've done several live mixes, I've never experimented with adding reverb to the whole mix. Does anyone have experience with this or suggestions? If so, what plugins, or hardwear units were used and how. Any tips and tricks would be much appreciated.

Applying Reverb on the whole mix.