10 weeks in Europe

First I would ponder where will be the best place to spend the holidays.
Next, I would think about what types of activities you wish to--If you have more city plans for the other places, then it matters less when you are there. Since you can't do all of those for three weeks (in some cases you have listed a city and in others a country), flesh that our part a bit more.
Last, scope out flights, will it be better for you to fly open-jaw, or since you have a lot of time, will flying to the best/easiest flight you can get (London as a possibility) and fly from there to/from your other destinations.

Lucky! I can't wait to be able to travel more than 12 days. I'm at least a decade behind you...

Think about flying south to begin your trip and then work your way north. Spend most of your time in the south, December and January in Northern Europe can be miserable weather wise. Think Vancouver but colder! Without knowing your interests it’s hard to make suggestions but Sicily might be of interest. Somewhere like Lecce or Taranto in southern Italy night be a good base, especially if you rented a car to visit around the area. Where in Germany? Munich is a good base for the southern area, Berlin offers a lot for visitors. From Amsterdam it’s easy to visit Brussels and Bruges for a few days visit. Easy to fly home from Amsterdam; if you choose to fly south to begin your trip, fly into Rome and then fly or train to destination….

You are Canadian and probably can handle cold weather better than me, but it will be cold in Europe in the Winter. Dress warm, take gloves, hat, scarf and overcoat.

I suggest starting in Belgium or Holland, one week is enough for Brussels, Brugges, Ghent before moving into Amsterdam, suggest a week in that city with more time to visit the Hague, Delft, and the countryside (windmills in zyder zee). Moving south down the Rhine, stop in Arnhem, the site of a major battle in WWII (Market Garden, featured in the movie, A Bridge Too Far).

Then to Cologne to see that magnificent cathedral, further moving down the Rhine all the way down to the Black Forest and Strasbourg, France. On the way don't miss Rudesheim for a Rhine cruise, Mainz, Frankfurt, Heidelberg and more.

From SW Germany head toward Bavaria. It is a bit out of the way, but you would go to Rothenberg Ob Der Tauber on The Romantic Road, taking it to see some great walled medieval towns as well as Augsburg and Oberammergau to Fussen.
The take in Garmish and the Zugspitze, then up to Munich and perhaps Nuremberg. If you have time some days in Berlin, if not head to Berchtesgaden and Salzburg, Austria. Then on to Vienna/

You probably need 3-4 weeks in Germany and Austria.

Finally in Italy, Tuscany, Florence, Sienna, Lucca, Pisa, Cinque Terre, then to Perugia, Assisi, Spoleto and Orvieto before Rome. Rome deserves at least a full week. Then down to the Naples area for a week. Suggest staying in Sorrento to see Capri, Pompeii, the Amalfi Coast and Naples.

Thank you for the replies! Still unsure how this will go but now have a bit better idea how to plan.