Here is the spark plug replacement procedure:
Although the manufacturer does not specify a replacement interval for the plug connectors (boots), personally I would recommend replacing them with new ones while the plugs are out. Nothing lasts forever, and it is much more convenient to replace them as part of this job rather than later at some pont when they degrade enough to allow a misfire condition to develop. These boots are usually around $10 each from most parts stores.
It is always a good idea to apply a small amount of dielectric grease to spark plug wires or boots when installing them, to make removal easier in the future.
At 100,000+ miles it would also be a good idea to consider replacing the fuel filter, transmission fluid, and engine coolant as part of a comprehensive maintenance service.