As for places to visit in Italy, it's hard to go wrong no matter where you choose to go. What's best for you really depends on your interests and expectations. Certainly Rome, Florence and Venice are beautiful, historic cities with a lot to see and do and highly worth visiting if you've never been to Italy. Rome has the ancient Roman sites, many museums and galleries, the Vatican and the beautiful piazzas and fountains. Florence has great architecture and spectacular art. Venice has the canals and bridges and beautiful buildings and art. All three have excellent food and festivals depending on exactly when you visit. If you're interested in scenic beauty, then places like Cinque Terre, the Amalfi Coast & Capri, the northern lakes and the Alps would be good for you. Or there are the smaller cities like Verona, Bergamo, Trento, Bolzano, Polignano al Mare, Montepulciano, Montalchino or many other places would be good. There are the beaches of Sardinia, Sicily and the Versillian coast or Rimini/Riccione/Gabicce Mare, Lucca and other places. You can visit San Marino, a small country completely surrounded by Italy.
There are thousands of local festivals all over Italy. You could look for places with something going on when you plan to visit and get a little more insight into the local culture. Bologna doesn't have a huge old town left, but the remaining parts are nice, there's excellent food and good nightlife with the university there.
Go to your local library, find the travel section, get books on the UK and wherever else you'd like to go, and sit down and READ. This is called RESEARCH.
Once you have an idea of what countries you'd like to go to, and what you want to see and do - all of those countries have a lot to offer, and this is even before you start looking at other countries in Europe. Are you into art? Sport? Music? History? Or merely having bragging rights? Base your choice on that .... then come back and ask particular questions.
The question is not about what countries to visit, but which cities, regions in each city. Over a short period, say 2 weeks, you can easily visit London, Paris, Rome, Venice, Florence.
Each of the countries you named have an immense number of places of interest which may or may not appeal to you. Then there is a matter of time of stay in each one and ability to travel around in order to see more than the obvious sights of their capitals. Even that can be a matter of long staying and not be able to see everything.
My suggestion is to google each country and do some reading
you could spend years seeing everything of interest in Europe
you really should make an effort to zero in on what takes your interest
some want to the major cultural and historical landmarks
some want to see the studios U2 recorded their best work in
so .. think about what piques your interest and get back to us
or better still
buy a tourist guide the Europe and do some reading
or
just do some reading generally
Greece is a beautiful country. There are so many different islands and they all have their own unique characteristics. Then there is the northern part of Greece which has mountains. Central Greece and Peloponese-the southern part of the country which is also very beautiful. My favorite part is the island of Rhodes, magical place which has a little bit of everything: culture, beautiful beaches, old architecture, delicious local grown food, fish, etc...
Croatia
You decide. This takes a lifetime.
Don't go they don't want you stay away!!!!!
