What could cause fluttering gauges when you turn off a 1999 Saturn SL1 and a battery that drains whenever the car has not been started for a few days?

The most probable cause is an alternator with an internal short in the windings. This would cause the lights to flutter as the current being delivered isn't steady. It could also be drawing on the battery even when the car is off. If you can, charge the battery with a charger for a few hours,then reach in and feel the alternator housing. If it's hot to the touch, and the car has't been running for a while,the alternator is drawing from the battery and should be replaced.