Accurate Documentation (Drawings, Terminals and Networks), is vital for an efficient and speedy commissioning..

Monitoring of Motors 2I/2O ( Motor tripped, Motor Isolated / Reset overload and Enable motor forward).

Fit Inverters on DeviceNet as storing of parameters in EDS files greatly assist replacement of faulty units.

Linking all PLC's on a higher network such as Ethernet. Or just network the plc's together. 

Consider wireless Ethernet networks as it allows the diagnostics pc to get closer to the plant.