RS Turkey tour plus Independent travel for 2-3 weeks?

Both alternatives are doable. Depends what you prefer. Few years ago we did R.S. Turkey Tour. The tour ends in Kusadasi. We took a ferry to Samos. From Samos to Mykonos and then to Santorini. From there by ferry to Pireus and by subway to Athens. We had an open jaw airline ticket: to Istanbul and out of Athens. So you can think about this or similar options, too.

Elle, I would suggest that rather than fly round trip to Istanbul, you look at flying into Istanbul and home from Athens. I took the RS Turkey tour more than 20 years ago. I flew into Istanbul and home from Athens. When the tour finished in Kusadasi, I took the ferry to Samos and spent about a week visiting various Greek islands (Naxos and Santorini) before getting to Athens to fly home. I'd visited Greece before. Even 20 years ago, Greece was pretty easy to visit independently. I did my trip without any reservations or knowledge of the ferry schedule since it was before the internet. With all the online resources, it should be much easier to plan a trip.

Two or three weeks in the Greek Islands? WHat time of year?

Our trip is tentatively scheduled for mid-May through mid-June. For the two to three weeks following the tour we were considering a mix of a few days on a Greek island or two, then a few in the Athens area, and a few on the costal sites on our way back to Istanbul. We are not really beach lovers but would enjoy a few days with beach access.

Which way you go is personal preference. I can say that my mother (a novice traveler) and I (not a novice) found Istanbul easy to tour on our own, with the help of the Rick Steves Istanbul book. There's loads to see there, and your tour is only there for a short time. There is sufficient English spoken, English on menus, and the like, and the tram makes getting around easy (and if you stay in the Sultanahmet area, you can walk to many places). Do look into flying open-jaw (multi-city, into Istanbul and out of Athens), as this saves a leg of travel, and thus saves time and money. On the other hand, you may feel more comfortable seeing Istanbul at the end. It is a large city and can be a bit overwhelming for those not used to such places (I live in New York and my mother lives in Philadelphia, and we weren't overwhelmed at all, as the area of interest to visitors is only a fraction of Istanbul).

It is easy and fun to visit Greece independently. I agree with the others that you should book your flights into Istanbul, then out of Athens. After your tour is over, there are several places where you could ferry from Turkey to a Greek island: Kusadasi to Samos, or Bodrum to Kos, or Marmaris to Rhodes, to name three. From there, you have a wide choice of itineraries. There are more than 100 populated Greek islands, each with its own charms. You might want to look at the Thomas Cook Island Hopping guide, or a Lonely Planet Greece book, or Matt Barrett's Greece website, and see what appeals to you. Most first-timers to Greece focus on the Cyclades island group (Santorini, Naxos, Paros, Mykonos). Check out some ferry schedules (www.gtp.gr or www.openseas.gr). Spring/summer schedules may not yet be posted. But when they are, look for ferries from Samos to Mykonos, or from Kos or Rhodes to Santorini. You need not buy tickets in advance; you're just checking schedules. If you like places that are a little more off the beaten path, you might choose the Dodecanese islands instead. One easy itinerary would be to start in Rhodes and take the big Blue Star Ferry line all the way to Athens, stopping at various islands along the way (maybe 3-4 days each, depending on when the next ferry comes along). Look at www.bluestarferries.com to get an idea of this route. I personally love these little, lesser-visited islands that you will find once you leave Rhodes. The smaller islands feel more genuinely Greek; they can be very inexpensive; and the hotel and restaurant owners are so kind and grateful to see you! Almost everyone speaks English, so there are no communication problems. There are several Helpline posters with a lot of Greek travel experience; if you decide to do it on your own, you will find plenty of help here!