Good idea. Replace all 4 O2 sensors if you want to shotgun it (I assume you will do work yourself). It is extremely rare for a catalytic converter to go bad within 200,000 miles and they are very expensive. And O2 sensors in these motors are known to go bad with regularity. I have been to two different dealers who swore the cat needed replacing when it was only an O2 sensor after all.
If you want to save some time/money then just replace the two O2 sensors for Bank 1. Stick to the Denso brand sensors (OEM supplier to Toyota). I think I bought two from sparkplugs.com that were OEM and two more that were aftermarket Denso. Don't buy Bosch sensors for a Toyota no matter what compatibility is claimed by Bosch.
Here's a post I made about replacing the O2 sensors on an '01 Sequoia with a lot more detail:
Oxygen Sensor Part Number and Location