Colleen - We enjoyed traveling up from Naxos to Taormina, which was easily explored on foot. Sometimes Regent runs a free shuttle bus from this port to Taormina. The waterfront at Naxos also had some restaurants where you could enjoy a drink and watch the world go by. The excursion there to consider (if available) is the tour of Mt. Etna. Mt. Etna was erupting when we visited, so the tour wasn't run. That may or may not interest an 18 year old and her aunt.
Hope that helps!
Cheers, Anne
