While I think that most of the noise will be attenuated by the wood cabinet enclosure I will be building, I’m considering using acoustic ceiling tiles on the inside of the enclosure if I find the noise to be an issue. They are relatively thin and I think that the performance is pretty good when used in suspended ceilings. This possibility will be included in my design.
One thing I did not see mentioned here is the impact of large windows in the design. Unless they have two panes, they could transmit a significant portion of the noise from the router but I’m more concerned with the noise and performance of the dust collection system. Having a shopvac inside a cabinet will reduce the noise but the exhaust needs to be planned carefully to keep the noise inside and reduce the chance of overheating the shopvac motor.