My wife and I recently returned from a three-week trip to Europe and had a wonderful time. This is where we went and some recommendations:
Bruges (2 nights)
Absolutely loved this place. Make sure you do the canal tour and rent bikes to go in and around the city (check out the windmills around the perimeter) and get as much local beer as you can. Did the brewery tour at De Halve Maan. Great views of the city from the roof and had a Bruges Zot beer included with the price of the tour.
Rome (3 nights)
We were able to see the highlights in two days. Very crowded, hot in June and we can't say we had a really good meal while we were here. Overall very enjoyable, however.
Orvieto (afternoon)
Great stop if you're going in-between Rome and Florence. Easily accessible by train. Extremely impressive duomo, especially for such a small town.
Montepulciano (3 nights)
Perhaps our favorite. Not difficult to reach via train and bus, and the ride there is beautiful. Go to Osteria Aquachetta and the Contucci Cantina (as seen on Rick Steves). Rented a Vespa and did the Val d'Orcia route. CAUTION: if you rent a Vespa either don't do what I did and crash on the dirt road leading to Capella di Vitaleta (you should go there) or go extremely slow on dirt roads, watch for unexpected potholes and wear gloves! I lost a lot of skin on the palms of my hands.... Fortunately the rental company actually brought us another Vespa and we rode on.
Siena (afternoon)
Florence Jr. Feels more like a city than a small town. Consider skipping if you're going to Florence and are short on time. Beautiful duomo and panoramic view.
Florence (2 nights)
If you've never been there consider the Firenze Card if you have 3 days (advertised as 72 sites, 72 hours, 72 Euro). We stuck with the Uffizi Gallery (tickets purchased online in advance) on our only full day there. Watch "I'll Have What Phil's Having" on Netflix or PBS. We went to 3 of the places he visited on the show and loved all of them.
Lucca (afternoon)
Visit if you love biking and want to bike around the walls. A brief visit will do. Did two laps around the town in an hour.
Cinque Terre-Riomaggiore (2 nights)
Awesome for avid hikers. A bit crowded and perhaps a little overrated.
Lake Como (2 nights)
Stayed in Perledo (above Varenna). Spectacular views of the lake. Visit Vezio Castle and rent a kayak on the lake. Go to Bellagio for an afternoon.
Milan (afternoon/evening)
See the Duomo. Keep moving.
Overnight bus to Paris (supposed to be a train. The French rail workers went on strike.....)
Paris (4 Nights)
The Museum Pass is the way to go. Eat croissants at Ble Sucre, have a picnic, try the pho, go to L'As Du Falafel. See the sunset from the top of the Arc de Triumph and Sacre Couer. Make a beeline for the Denon wing of the Louvre if short on time/interest. Spend an entire afternoon at the Orsay and Orangerie. Splurge on a good meal at least once.
Flights
The biggest takeaway from this trip was to travel deep; not wide. Our plan was to use points on our Southwest credit card to fly from Phoenix to LAX where we'd take a really cheap flight on Wow Air to Brussels via Iceland and back to LAX from Paris. Problem? Turned out we didn't quite have enough points on the card to fly to LAX for free and Wow Air canceled our flight from Reykjavik to Brussels without sending out any e-mails, texts or calls. We ended up staying a night in Iceland (very expensive) and lost a day in Belgium. Our Ryan Air flight from Brussels to Rome was delayed by an hour, and instead of sleeping in a bunk on an overnight train from Milan to Paris we ended up sleeping upright on a 12-hour bus. Would have been cheaper and easier to have just bought a ticket from Phoenix to the destination we wanted. We had a great time everywhere we went but if I could plan it again or make a recommendation I'd say we should have either spent all of our time in Italy or done Belgium and Northern France.