First trip to Santorini

I have some friends going to Santorini in a couple weeks on NCL Jade. They have never been nor have I but I'm looking for some info for them. They want to go to the volcano in the morning and then a winery or beach in the afternoon. The volcano walk seems to be very high on the list however they are wondering which would be easier in the afternoon. Beach or winery..... or something else that you can't miss while in Santorini? Possibly their only trip there ever so they want to see the must see places. Any help y'all can provide will be helpful. They came to me for advice and I literally have no idea.