Whatever you do, don't travel through Europe in July or August, as half of Europe is on the road in these two months and everything tends to be overcrowded and over priced.
Best to fly into Milan, rent a car and hit the French Riviera (Monaco, Nice, Cannes, St Tropez) for a week or so, then go into the smaller cities of Toscany and Umbria in Italy - places like Pisa, Torre del Lago, Peruggia, Orvieto, and many others. Romantic, good food, lots of culture and not as overpriced as the bigger places. Include Florence for a cultural climax.
Then get rid of the car,
Jump on a train to Como, spend a day or two, take a boat across the lake past Bellagio to Lecco or any other place with a train station on the other side. From there you can take trains via Posciavo to St Moritz in Switzerland. Spend a day or two with the rich and famous there and then take the famous Glacier Express Train through the Alps to Zermatt. From there go to Montreux for a couple of days
From Montreux you can take a boat to the French Spa Town of Evian (where the water is from) and win all the Euros spent so far back in the Gand Casino (or not).
Then off to Paris with a TGV high speed train from Lausanne or Geneva.
From Paris you can easily get to Brussels and Bruges. If you like you can also build in London after that.
If you want to include Prague, fly there from London for two or three days.
