Change of plans-- first timers in europe

Why do you want to see Brussels? Just curious; thus far it's been my least favorite city in Europe. Now Bruges/Ghent is a different story, but Brussels itself...meh.

I'd tack on a 3rd city either near Rome or London to avoid another flight (Rome to London is 3 hours, plus the couple of hours before and after to board/deplane, so that will suck up a full day of travel). Near Rome you could do Florence or Naples/Pompeii. Near London you can take the Eurostar to Paris or head north to Edinburgh.

Another great trip that combines cities easily by city-center fast trains is Amsterdam - Brussels (daytripping to Bruges/Ghent) - Paris - London.

Since you want to see multiple countries, there are some great Mediterranean cruises that start in Rome and go to Livorno (Florence/Pisa), Genoa, Nice/Monaco, Marseilles, and end in Barcelona. Alternately if you start in Rome and take the train to Venice, there are a bunch of cruises that leave from Venice and hit the Greek Isles/Athens, or Croatia/Montenegro. I like cruising because you travel while you sleep, so it saves a ton of time. Of course you don't get to delve as deeply into each city, but you do hit the highlights of a lot of locations, which appears to be your desire.

Check out Disney, Royal Caribbean, Norwegian for across-the-Med cruises.

You can do as options : Vienna - Florence - Rome or Lucerne - Florence - Rome

London and Rome could be your two new open-jaw cities. If you fly into London and spend a few days there, you can easily (just over 2 hrs) fly into Pisa (a bonus stop) and leave your luggage to visit the tower if that interests you, then a train to Florence. Spend a few days there and another train to your final destination and departure city of Rome.

Alternatively, replace London with the city of your choice: Paris is also a great choice, if you find a direct flight at a good price.

It will be packed and you'll just scratch the surface with 2 or perhaps 3 days in each major destination, but you're young and energetic!

I don’t really like mixing countries as just when you begin figuring out how they do things, off you go to adjust to more differences. But it is your trip!

Why Brussels? The only reason I would return there is to eat mussels in their fish market area. It is my least favorite European city and I have been to most of Europe.
Paris and London are an easy pair, taking the Eurostar train between them.
If Rome and London, take a few day trips nearby these wonderful cities.
Rome day trips: Tivoli Gardens with Villa d’Este.
London: Windsor Castle
It will stil be warm to hot in Rome so go to London first. Enjoy your first taste of Europe. I predict you will have many more trips there.

London- Florence- Rome
Or London-Paris-Rome
I love cities. Most bang for your travel buck. Enjoy

I tend to focus on one country now but in my youth we traveled several times to Europe and went to multiple countries. I really enjoyed the contrast between the countries. And this is in the days when we took an overnight train from Paris to Rome.

So if I was going to do this now I would go to London, Paris, and Rome. Very different from each other.

And fly to Rome!

I have also been to Brussels and I too would not rate it as a favorite place.

Don't do Brussels, about the only thing to see is the Grand Plaza.

If going to Rome, stick with Italy and visit Florence and if possible Venice.

Barcelona is a long way from Lisbon, if you do try to squeeze in Portugal and Barcelona, recommend you fly.

Portugal deserves some time. If you have 11 days for Portugal, do 4 in Lisbon with one day as a day trip to Evora. The a day in Sintra, perhaps on to Obidos, Navarre and Porto (2 days there as well as taking a cruise up the Douro or the train.

London and Rome are too far apart, a train ride would be expensive and time consuming.

I'd do the classic Venice - Florence - Rome. Fly in to Venice and out of Rome. Perfect for 11 days.

If you want to do London and another city, add Paris as it's such an easy trip on the Eurostar between the two!

Two years ago I flew into Milan, stayed 2 days, took a train to Venice, stayed a few days then train to Florence. In Florence I met up with a friend. We stayed 5 days there and took a couple of day trips. One was truffle hunting in the hills right above Florence. That was so fun! Another day we took a train to Bologna where we met up with a tour group to tour a Reggiano-Parmigiano cheese factory, a balsamic vinegar factory and finally a prosciutto factory. From Florence it's only about a 2 train ride to Rome.

I've been to Europe 12 times and Florence and London are my favorite cities. Brussels is my least favorite. If you go to London, I suggest that you fly into London and out of Rome. Since this is your first trip, going to London first would give you an easy first destination when you are jet-lagged.

@vanessa Those tours sounds amazing! I looked it up and found something similar but looks like its $300 pp. A little pricey for us but looks like a great experience!