Fuel, based on what I'm seeing here, it doesn't look to me that you are in dire need of a new O2 sensor. Unless you are experiencing some sort of low mileage or other malfunction that leads you to it, I would go away happy.
If the car has high miles and you think that it has never been changed, by all means do so, it'* your money and car and you probably know it best.
Just be aware of the "trap" that having a sensative scanner tool can lead to. That you will see all the little variations and hiccups that are part of daily engine use and that the PCM and other monitoring devices moderate all the time. Also, it leads to a lot of questions we would never think of if we hadn't seen this or that on the screen.
I'm not trying to minimize any possibilities or issues that may really exist, just writing a note of caution.
Mike: 1997 SE w/ 183K, aka White Horse
, Gutted Airbox w/K&N, drilled 180* t-stat, tint all around, clear corners w/SilverStars, "PONTIAC" light up tail, PEMs, NGK TR55s