We are traveling from Rome to Amalfi, Italy (Grand Hotel Excelsior), what is the best (easiest and most affordable) way to get there?
Train from Roma Termini to Salerno and a ferry:
http://www.travelmar.it/downloads/orari_travelmar.pdf
It's a ten-minute walk to the Concordia dock from the station. For a google map of both enter Salerno Travelmar Ticket.
That would be my suggestion too. From the train station, it's all level and paved, slightly downhill.