Turkey 13 day tour- pre and post travel suggestions

I did this tour last fall, and we added several days to Istanbul before the tour, and it still wasn’t enough time. I would suggest looking at the tour itinerary for the Best of Istanbul to see what it covers, and decide how many more days you need. There are some great museums and other sights that the Best of Turkey tour doesn’t have time for. At the end of the tour, some people take a ferry to a nearby Greek island.

Definitely add at least two days ahead of the tour start date. I recommend taking the food tour if it is offered (look at your tour details page, there will be a note about it) it is always the day before the tour starts. It's on the Asia side of the city and you will get a really wonderful (literal) taste of Turkey before you head out.

The ferry options from Kusadasi are pretty much to Samos, Greece, or other parts of Turkey so you have limited options there. If you go to Izmir there might be a few more ferry options. There aren't good train options to any of your listed cities unless you want to spend many days getting to your next location. I suggest for efficiency purposes, your best bet is to fly somewhere from the Izmir airport. There are plenty of direct flights to all parts of Europe, and you don't necessarily have to fly back through Istanbul. This site lists all the direct flights, though not all go on every day of the week https://www.flightsfrom.com/ADB. Your tour bus will do a drop off in the morning on the last day of the tour, so you could be in your city of choice by early afternoon.

We would prefer taking a train or ferry versus planes to extend our
trip. Towns of interest: Budapest, Dubrovnik, Bled, Vienna.

None of the towns you mention are realistically accessible by train or ferry. Flights yes. All are served by Turkish Air so you could build a nice multi-jaw or multi-city ticket with them.

• Ljubljana/Bled: not worth the effort from Turkey
• Vienna: 3 nights minimum and a nice stop over coming or going from Istanbul.
• Budapest/Vienna: 6 nights minimum and a great stop over coming or going from Istanbul.
• Dubrovnik: not a horrible idea if the flights work out well. 2 nights minimum coming or going from Istanbul.
• Dubrovnik, Perast, Kotor, Budva connecting to Istanbul from Podgorica and/or Tivat: 5 nights minimum and brilliant.
• Budapest: 3 nights minimum and a nice stop over coming or going from Istanbul. Favorite Tourism Video of Budapest https://youtu.be/1nd5AtZIrTk?feature=shared Anthony Bourdain describing how visually pleasurable Budapest is https://youtu.be/0nd9DuDGCz0?si=aa0c19KaJHEtabkX

Your advice is just what I was looking for to begin our trip planning. Thanks to everyone. Would a river cruise including Vienna and Budapest with an out fit like Viking be advisable?

If a river cruise is the sort of thing you like, many do like them. Not sure there is one that short (Vienna and Budapest) and not a whole heck of a lot to see on that stretch of the river but the boat experience might be something you enjoy. OR, just take the train, its only 2.5 hours and you could do it up in First Class or if you go RegioJet they have have a first class that looks pretty amazing with full service and its less expensive than a full price OBB 2nd class ticket.

The Business comfort class means premium service and maximum comfort. Above-standard features with leather seats, entertainment portal, Wi-Fi and priority service by our staff. Rajec water, Illy coffee, juice or Bohemia Sekt Brut sparkling wine are provided free of charge, as are newspapers and magazines. Our on-board menu with a variety of snacks and beverages is available. The comfort of the Business class is the best option for everyone who wants to work or relax during their journey with above-standard service.
Free Prosecco or juice
Refreshments
Free hot drink
Air conditioning
Silent compartment
Free juice
Steward
Priority service
Newspapers
Free water
Wi-Fi
Power outlet

Your advice is just what I was looking for to begin our trip planning.
Thanks to everyone. Would a river cruise including Vienna and Budapest
with an out fit like Viking be advisable?

You might check Cruise Critic for more input on that topic, or do a search in this forum on Viking cruises (they definitely get mixed reviews).