If you are using traditional spray heads, you might consider converting these to rotating micro spray heads (ex. Hunter MP1000, , etc.) which are simple replacements for Rainbird style spray heads.
This provides greater throws (if necessary), less aerosolation of spray, less run off due to lower precipitation rate, and also allows approximately 2-3 X the number of spray heads on the line as with traditional spray heads because the flow rates for each head are less. Watering times are longer because of the lower precipitation rates. However, the lower flow rates may allow you to combine some of the pipes to being controlled by a single valve such that you no longer need so many valves to control.