Most of my theater work is basically mono.
There's no point to panning the wireless mics attached to actors. Even if you could track them across stage, the very reason for them to be there is so audience members sitting further away from the actor can still hear. Panning the reinforced sound towards where the actor really is would be antithetical to that goal. If anything you'd want to pan the other way!
More subtly, panning the band is sub-optimal. Reason being that in many houses, a significant part of the audience is covered by only one speaker. If you were to pan the second woodwind hard left, for instance, half the audience would hear too much flute in the final mix, and the other half would hear too little.
You can pan a little, depending on the house, and this can help to open up a congested mix. But it is something best done in moderation, with an understanding of the compromises that may result.
In relation to that, one trick for getting vocal clarity (particularly important and difficult in underscored dialog) is to send the wireless reinforcement of the actors to one set of speakers, and the band reinforcement (or for some shows, the pre-recorded backing tracks) to another.
This leverages the Cocktail Party Effect: the way the human brain is able to sort out one specific voice from the surrounding noise...if given localization cues.
In smaller houses, the direct acoustic energy off the stage is your friend here. If the first impulse that arrives at the audience member's ears is from the actor on stage, this helps their brain sort out the dialog they are trying to follow from the surrounding energy of band, ensemble, sound effects, and general stage noise.
Making this even more useful is what is called the Precedence Effect or sometimes the Haas Effect. This is another aspect of the built-in human signal discrimination; localization occurs upon the first impulse if it is within a few dB (up to -10 dB in fact!) of a stronger but later signal.
What this means, is if your reinforcement signal chain is delayed by 5-15 milliseconds, the audience members will perceive the sound as coming from the actors, not from the speakers. Even if the speakers are louder than the actors!
Tangentially related to this is the Broadway anti-flanging trick of sending each actor in a duet to a different signal chain; the so-called "A-B" reinforcement method. This reduces the disturbing sound that arises when an actor is getting picked up on two different microphones at the same time (a situation that arises far too often in the romantic plotlines of the golden-age musical).
However. However. Of late I've been doing a number of musicals that are more akin to the Brill Building than to Broadway.
This takes a little explanation. For a classic like "Oaklahoma!" the illusion is that we are out in the wide-open prairie with Curly, Laurie and Judd. Orchestral music swells in the background, and the people sing to us from where they stand on stage.
For a musical like "The Wiz" the illusion is of a Motown studio session. Loud, compressed, artificial sound, band and effects and wireless all rolled together in to a single seamless mono mix.
The main advantage this gives me is that I don't have to try to taper my reinforcement speakers to try to mimic the inverse-square falloff of the acoustic energy from the stage. Instead I am running a hot system that blasts right over the stage, and is essentially flat from the front seats to the rear of the theater; every seat, therefor, hears the same show.
It also means the whereas for a show like "Sound of Music" I took every chance to back off the reinforcement into naturalistic, near-invisibility, for this show the dialog is all run hot as well. There is less of a division between song level and dialog level.
(However, this still doesn't release the FOH mixer from being conscious of the tendency for levels to rise. You have to watch yourself, watch the meters, and consciously back down at intervals lest you end up having the system peaking well before the 10:00 number.)
(This bears expansion. When you run hot, hearing fatigue sets in. It sets in on you, on the audience, and even on the band and actors. Even if your system could keep going up and up indefinitely -- if you had unlimited headroom and there was no such thing as feedback -- you rapidly reach a point of not just diminishing but paradoxical returns. With every increase in volume, hearing fatigue increases faster and the sound becomes perceptually softer and more dull-sounding. This process continues to accelerate until the audience is temporarily deaf and nothing you can do will help them hear the nuances of the next piece of dialog. So watch those meters, check your own assumptions frequently, and take every chance offered by a slow scene or a soft song to back down again. And then you will have the reserve power for those show-stopper numbers.)
I'm also, for the first time in this building, running without delay.
Usually I have up to 40 milliseconds delay on the reinforcement, leveraging the Precedence Effect to make the actors on stage the apparent source of all the audio energy. In this case, I have no delay other than the physical distance (and the corrective delay between the different speakers of the multi-speaker setup). The reinforced sound is the first thing to hit the audience, and all the noise from the stage and all the leakage from the pit orchestra follows in time.
And that I think has given me an unusual clarity for this house. By presenting the reinforced sound to ears first, they are able to get crisp, time-aligned waveforms. The smear of sound propagated acoustically from the stage falls behind that first peak.
As part of this philosophy, I've been doing a lot of effects designs that are similarly presentational.
In a realistic effects design, we pan towards where the sound is supposed to be occurring. Actually, this is just the start. We set up specific and unique speakers for effects. We position speakers carefully to allow their sound to "Worldize" into their environment (a toilet flush sounds best, for instance, if you put the speaker in the part of the set that is standing in for a bathroom, and let the sound echo in a natural way around the set walls).
I've gone further, using bell ringers to make an actual phone ring on stage, putting speakers into an intercom box, even once using a live walkie-talkie on stage.
For a presentational effect design, the overarching concept is that what we hear as an audience is non-diagetic.
(The story is told by I think Alex North, who was asked by Alfred Hitchcock during the filming of "Lifeboat" where the orchestra was supposed to be in these scenes out in the middle of an ocean in a lifeboat away from everywhere. The composer asked the director, "Where are the cameras?")
Anyhow, look no further than film or television comedy for non-diagetic sounds. We don't suppose the "Waa waaa" trombone is actually in the scene! (At least not mostly -- there are a number of classic comic moment when what was assumed to be non-diagetic turns out to be quite "real" -- at least to within the fluid reality of a comedy.)
So you conceive of sounds that reinforce the action or the emotion but aren't pretending to be the actual sounds of some actual thing on stage. But even when the sounds are natural to the environment being presented, I have been tending in many of my recent designs to present them as part of the total mix going out the speakers. Instead of sending an effect to stage speakers and pretending there is a pirate ship on stage, I send to the mains along with the orchestra and pretend we are watching a show that is presenting the idea of a pirate ship.
Sounds subtle, I know!