Does anyone know how to get around the greek islands is Feb? Is anything open?

Greece has an excellent ferry system that connects many islands. You can see most routes here: http://www.greeceathensaegeaninfo.co...erry-chart.htm It doesn't show Santorini>Rhodes/Kos but it does exist.

Some routes are not available during the winter months because of the lack of tourist demand.

Almost all shops, hotels, restaurants and galleries are closed during the winter but there are a few that stay open all year to service the local population.

Ferry schedules: http://www.gtp.gr

Any special reason why you want to go to the islands? There will be much more to do and see on the mainland, and most things will be open. Some people enjoy going to the islands in winter, but they are usually long time visitors who have friends there.

In February I would much rather base myself in Athens, perhaps doing a trip to the Nafplio area to see the many nearby archeological sites. Greece has a very good bus system on the mainland, and you can travel around with no worries about weather stopping ferries.

Islands that have "life" in winter are the ones with a larger permanent population.
Here are some of them : Corfu, Lesbos, Samos, Chios, Syros, Rhodes and of course Crete.

The other ones and especially the Cyclades islands ( Paros, Naxos, Mykonos, Santorini etc) will be sleepy, to wake up in April/May again.....

The mainland as Heimdall suggested would be a much better option

thank you all so much! Any suggestions on hotels? Or even hostels? My kids are doing the traveling and they are 22 and 25.

Have they decided where they will go?
Before we start recommending hotels it would be good to know their itinerary.

A good source for hotels reservations is www.booking.com