There are so many places to see in Europe and so much to experience.
I love Spain, and it's great cities of Barcelona, Seville, and Madrid. One of my favorite areas is the Basque region and the city of San Sebastian. From there you can easily travel across the Pyrenees to coastal France or west to Santiago and many wonderful Spanish towns. Spend a few weeks or a month driving from Barcelona to Gibraltar to Seville to Madrid to San Sebastian across the Pyrenees to France and back to Barcelona and linger awhile there. It is a wonderful city. The Gaudi architecture is not to be missed. And the people are welcoming and fun.
Italy is also a very special place. It's cities of Rome, Florence, and Venice are really places where everyone should go once in their lifetime. The Almalfi Coast is spectacular and driving it keeps you alert. The cities and towns in Tuscany like Perugia, Spoleto, Assisi, and Orvieto are charming and restful and have great food. I have spent some time in the area north of Milan on the lakes bordering Switzerland. Lake Como and Bellagio are great memories. Sicily is also worth a few weeks exploring. Lots of Roman history.
The Algarve, the south coast of Portugal, is a very pleasant place to visit. Need a automobile, but easy to day trip fron Albufreria to the east, west and north into central Portugal.
Of course, there is Paris, one of the great cities of the world. France is again a good place to take a month driving from Paris to Normandy and to the south of France. Great vineyards, great food, wonderful towns and inns. Outside of Paris it's worth knowing some basic French words and phrases.
While England can be rainy and cold, the summers are great and there is so much to see outside of London, which is also a great starting point on a driving trip. Especially enjoyed Cornwall, Wales, the Lake District, and the towns on the English Channel. Ireland was great fun. Galway, Killarney, Cork were nice adventures and Dublin was special.
Traveled from Amsterdam to Budapest on the Rhine-Main-Danube river system. Travel on ocean going ships in very easy, restful, and allows one to experience a lot in a short time. Travel by river boat is even better.
I have been to most of the Baltic countries - Sweden, Denmark, Finland and their wonderful cities like Copenhagen, Stockholm, and Helsinki. Need to return and spend more time.
The countries of of eastern Europe are on my bucket list. Want to see Prague, travel more in Germany, and get to know the Balkan countries and the wonderful places on the Adriatic Sea. Think an extensive Eurorail trip would be great.
Holyland travel was a great experience. Loved visiting Nazareth, the Sea of Galilee, the Dead Sea and Jericho, the Jordan river, Bethlehem, and Jerusalem. Christian, Muslim, Jewish - a city of the ages. Everyone should go once in their lifetime.