Athens to Santorini

Budget and month would be helpful.
Generally speaking Fira is the capital and has that great Caldera View. Next most popular place is the village of Oia on the west end of the island. Also with outstanding views. Both are quite expensive.
The village of Imerovigli has the Caldera views and is a bit out of the way so is a bit less crowded at sunset.

You can also get a caldera view from Firoestafini a suburb of Fira. It is just far enough away from Fira that it is less expensive. You can also look for a hotel with sea view. It will not have a Caldera view but it will be less expensive.

Another place to look would be the lovely walled village of Pyrgos has great views and less tourists.
Lastly Santorini has a gritty volcanic sand beach at Perissa village.

We always stay at Firoestafini.
Santorini has a great archaeological site at Akrotiri and several wineries that give tours and tasting.

The Greek airlines that will fly from Athens to Santorini would be Aegean and Sky Express. Both are good airlines. Seat sales generally start around Christmas time. Sign up to Aegeans web site for sales announcements.

Here are some images of Santorini
Santorini https://www.flickr.com/photos/stanbr54/albums/72157632154800782

We stayed in Imerovigli and it was amazing. Much less crowded than Fira and Oia and the sunset views were sublime

We have used both Aegean and Sky Express. Both were good.

We took Aegean Airlines from Athens to Santorini and had no problems. I signed up to receive e-mails from Aegean and they do run sales once-in-awhile. We stayed at Lithies Traditional Homes in Firostefani. The sunsets and the view from the terrace outside our room were spectacular. The rooms are beautiful, they treat you wonderfully and it is an easy walk into Fira which is more touristy with shops and restaurants. Another plus is they arranged complimentary transportation from the airport and back and they took our luggage down and up the steps to the hotel. Hope you have a great time on your RS tour. We are doing the RS Best of Switzerland tour in a few weeks.

Thanks to everyone for the responses. No budget established but flying first class and looking for 5 star resorts in all locations. Flexible on dates but thinking of May or September. I'll contact the airlines you recommend and see about booking flights to the islands. We have taken 3 RS tours in the recent past, this one to Greece will be on our own. Putting to use the travel skills they taught us. Thanks again.