The automatic transmission has to be the most vexing, heartbreaking, wallet-busting component of a Saab 9000.  If you must have an automatic transmission, you might do well to look at some other car.  At least one owner reports wonderful success with Saab automatic transmissions, but he clearly stated that he never pushed his cars very hard.  He also honestly stated that he changed his transmission fluid "when he thinks about it".  Other owners have treated their auto transmissions to all manner of specialty fluids and changed fluid and filter regularly and often, only to have the transmission fail.  The consensus seems to be that you can expect 80 to 100 thousand miles; some will fail earlier, some later.  Some will beat all the odds.

Many automatic owners feel that the Saab is the best automatic transmission they've ever driven, as far as performance is concerned.  So if you must have an automatic, it's a good one; just be prepared to replace it at some point.  And it is pretty expensive.  No, honestly, it typically is damned expensive.

The moral of the story appears to be this:  The Saab automatic transmission will benefit from being driven gently, and maintenance probably won't make up for driving abuse.  Even if you maintain it religiously and drive it gently, the outcome is uncertain.  If you want to drive a Saab the way it begs to be driven (turbo, anyway), then buy a 5-speed.

Symptoms: Erratic behavior of any and all kinds - won't go into gear; hard shifts; erratic, jerky shifts; shifting too soon; shifting too late.  Has been known to fail completely with no warning whatsoever.  

Preventive maintenance: Buy a 5-speed.  If you do buy the auto trans, change the fluid and filter at least every 24000 miles.

Hint (THANKS to Oliver Temple):   Apparently, there is a tendency to overfill.  The fluid level changes with transmission temperature and, like all auto transmissions, should be checked when up to operating temperature and on level ground.  "To do this you need to get the car up to normal running temperature, then put it into Drive for 15 seconds, then Reverse for 15 seconds, then to Park.  Leave the engine running and check the level."