14 Days - Greece, Italy, Turkey will this work?
 

Looking to travel with my wife in September to Greece, Italy and Turkey all in 14 days. Spending about 4 days in each country.

flying from Canada to London England and then flying from there

Greece - Athens, Santorini (thinking about a ferry from athens to santorini then flying back to athens to fly to one of the next desitations)
Italy - Rome, Venice (flying into rome, flying to Venice then flying out from venice?)
Turkey - Istanbul

Any thoughts or recommendations on this trip? is there a particular order that I should do? should I swap out cities? is this too much in too little time?

I don't wish to be rude but I think this is a crazy idea. It sounds exhausting and not very rewarding as you'll see tiny snippets of each country and lots of the insides of planes and trains. It's also an environmental issue to take so many short flights. I encourage you to think quality over quantity.

It's busy to begin with. If you start back tracking it gets worse.

There are flights showing Santorini to Rome in September.

I'd avoid flying into London unless you want to visit that also. Much more sensible would be a direct flight to one of the three countries.

But ya it's too much for 15 days unless you're touring airports.

Yes!!! Way too much in too little time!

Get some guide books. Start with a Rick Steves (for nitty gritty, how to, history, etc. information) a Fodors for sights, hotels, towns, cities, and perhaps a National Geographic for maps and pictures.

Is this your first time to Europe? Do you have personal interests in the places you picked? What are they?

Do you wish to see any major sights (museums, churches, archeological sites, etc.) most people go to see or do? Any of the tours, walks, sight seeing experiences in any of those places or simply touch down, get into a city or countryside for some walking and head out again?

Is your total trip time 14 days or do you have 14 whole days, not including there and return, (15 nights) on the ground?

Have you tried mapping this out with travel days?
When calculating travel, be sure to include the whole time, getting from the hotel to airport or train station, check-in, security, etc? Boarding, flight, departing plane and getting from airport to next hotel. Do not make the mistake of counting travel days as sightseeing days. There may be an evening for walking and dinner, but with the distances you are considering, that is about it.

I calculate you will spend at least 7 days traveling with only 7 actually for sightseeing, not a very good ratio time or money wise.
You can see a lot more by traveling less and seeing more great places closer together. Example: if you are going to Greece for the archeological sites, consider going to some sites in Italy instead, different, of course, but Pompeii comes to mind. If you are going to Santorini for the sea and views, consider the Amalfi Coast. Save two days of travel plus cost of flights.

You could go to:
Any one of these large countries that are super loaded with mega sights and experiences, or
London and bit of Greece
London and a bit of Turkey
London and a bit of Italy

If you are mainly interested in the outstanding historical sites and museums of the megacities Istanbul, Athens and Rome, this trip may make sense. But be aware that you will see almost nothing of Turkey, Greece and Italy. Four days for a somewhat serious visit of each of the 3 caapitals is a absolute minimum:
Christian and Islamic Istanbul with the big museums, a Bosporus trip and a excursion to the Princes Islands;
Rome and Etruscan necropoles around;
Athens - Dafni - Korinthos - Mycenae - Nafplion - Epidavros.
There will be no time for Venice and Santorini.

Save Turkey for another time. Fly in and out of Santorini. A ferry takes too long. You'll waste a whole day. 2 weeks in each country is the minimum I would recommend, but if you only have 2 weeks stick to either Italy or Greece.

If invited on a trip like this, I would refuse to go.

I suggest these essentials for your Istanbul trip:

Hagia Sophia, Hagia Irene, Blue Mosque, and Basilica Cistern are in the same area. You can spare a full or half day in order to visit them. After that, you can go to Galata Tower and view the stunning landscape of the city. Also, you can find many cultural things to dos near the Taksim district. If you like boat trips you can take a boat trip on Bosphorus. Eventually, Istanbul is a very crowded and huge city. However, those popular places are very close to each other and four days are enough for these attractions. At the end of this intense trip, you should relax at the traditional Turkish hammams.

Wish you have a good journey.

More practical advice: Why fly through London? There are more efficient ways to fly from Canada to the two mainland countries you choose. If you enter your departure and destination cities into a multi-destination search function, repeating with a different departure city to come home, it will collect the routing alternatives for you.

The OP has not responded. Perhaps they changed their mind.

In case the OP responds, I agree with everyone else. This is a crazy itinerary. I would spend 2 weeks in one country. You choose the country based on your interests. If you choose Greece, look for flights from Canada to Santorini (you will change planes somewhere, either in Canada or in Europe, depending on where you are flying from in Canada.) We just returned from Greece with an awesome itinerary that included Santorini, Naxos, Nafplion on the Peloponnese Peninsula, and Athens, to give you an idea.