My vote would be to drain and fill, drive a bit, and drain and fill
again:)
Do you drive your car like a NYC taxi, stop and go all day in summer
heat? If not, then chances are that the tranny needs only a mild
maintenance.

I did a drain and fill (only once) on my wifes 98 Altima (99% pretty
much the same as yours) after 120 K miles. She said it was like I
brought new life to the car. What I noticed is that the car is much
more willing to downshift, and therefore feels more spirited, and I
feel totally confident that her car will go way past 200K miles
without any major engine or tranny issues.

On a side note: I un-plugged the relay for the foglights so that she
won't accidentally turn them on. The foglights put a 15 amp drain on
the ALT and she's never aware that she turned them on. Pulling the
foglamps relay will make the ALT last longer because it will run
cooler.

CD

You can flush it yourself if you're up for it. You can pull the pressure
line off the trans (usually the one with the banjo bolt) and run it into
an empty gallon jug. Start the car and wait for the jug to fill. When
it's full (a minute or two), shut off the engine and put in a gallon of
clean fluid. repeat until the fluid coming out is bright red. Usually 2
1/2 gallons or so. You'll probably need 2-3' of 5/16" hose.