need to be careful with stratification ...... RA temp may be a few degress higher than occupied space if RA is collected at high level in a very tall space ..... play around with offset to "compensate/falsify" the sensor output.....
Other answer is to put RA sensor beside the seat where you sit most ...!!!
I agree with Imok on both his replies. However a better description of your system and what control action you require, will clear the matter in a better way.
I think PaulKeating has a point about stratification, particularly, as you said this is a theater. How about multiple sensors in the controlled space and averaging them?
If you really want to control the supply air temperature, then you must install the sensors in the supply air duct work. You can then control the supply air temperature to any condition you want.
I totally agreed with quark
more sensors shall installed inside the threater (low level perfer) to measure the indoor temp. of the threater and than averaging them. It is more accurate than simply place the sensor near the return air louvers.