One of the best units people can look at is converting to a bi or tri fuel combination. A generator that can run on gas, propane or natural gas is a unit that can extend its versatility. As fuels can be used that you don't have to worry abut their stability over time. Even where I work our Giant generators are set up to start on Diesel than convert to Natural Gas if it is available. Having a second unit to work in conjunction with the other unit is good way to go, as one unit rests and is being serviced with fuel/oil change/ cooling down, the other can pick up the slack. Prevents them from burning up.
Good grounding rods can make a huge difference in the performance of the engine, more so if it is being used for any form of power of communication devices, as it will reduce static/interference.