If you know which end of a screwdriver to pound on you can try a quick trans adjustment/tune up. The net can help with actual specs on band adjustment. That and the time involved in pulling the pan bolts if you don't have a power wrench are the hardest to do. You'll need an INCH pound torque wrench. That is the only unusual tool.
Go with a fluid and filter change, you may be amazed at the difference. I've seen cop cars from back in the day that I thought would need a rebuild work perfectly for another 50,000 miles of severe usage.
The possible DOWN side is that if the fluid has never been changed the fresh fluid can knock loose deposits that can plug stuff up and require a rebuild.