I will be travelling form rome to Amalfi coast by train, overnighting in one town, returning back to Rome for about 6pm, for a late evening flight out. I've never been to the Amalfi coast, and would like to see the coast and also enjoy a coastal town. Suggestions for a town to stay in, and the best ways to visit the coast and get to and from the coast from Rome?
Here's an RS article that may be helpful if you haven't seen it. http://www.ricksteves.com/plan/destinations/italy/naples-sorrento-amalfi-coast.htm You don't say what time of year you will be traveling. Does your flight leave at 6pm or is 6pm when you need to be at the airport?
Assuming you are traveling during the summer, you could take an early morning train from Rome to Salerno, and then a ferry to either Amalfi or Positano (the ferry stops at Amalfi on its way to Positano). Spend the afternoon in the town, spend the night, then take the morning ferry back to Salerno and then the train back to Rome. Personally, I prefer Positano.