Got a 2000 red coupe with 89k. Its a weekend warrior and doesnt go out much in the winter. It failed to start 4 weeks ago and I had popped a new battery in. The car started. It also started a week later; I ran it 20 miles. Next day, nothing: no clicking, no interior lights, nothing. Today I had the car jumped, and nothing: no clicking, no interior lights. Had AAA come over (they had put the other battery in) and they replaced the battery with a heavy duty model. Although they couldnt jump start it today, the car started with the new battery. Ran it all day, highway and local about 25 miles. Car acted fine.Went to put it in the garage, and no power. No interior lights, no ignition clicks, nothing. Stone dead. Can someone tell me what is happening here? Please help. This is very frustrating.

I have a very hard time believing 3 batteries crapped out so I would be on a quest for wiring issues.
Check all grounds & power leads including the ones to the starter. Everything should be tight. Also check the ground splices on the frame rail just in front of the alternator and in the same location on the passenger side.

As an additional check, press the "Gauges" button on the dash when it's running and see if the Battery Voltage is at least 13.5 Volts. If not, your alternator may be dying or dead. You can have AutoZone or an equivelent check it out for you as well.