I have been planning my dream trip for a few years now. I could only do the trip in December 2014 due to work and it couldn't have been a better time as there are no crowds and weather was great. Did this trip solo and flew into London for 3 nights, then flew into Venice Italy and spent 3 weeks taking the train down Italy. Cinque Terre, Umbria, Amalfi Coast & Capri should not be missed, truly stunning and magical. Single female in my late 30's and it was fantastic. Met so many wonderful people and best experience of my life. Rick's book made this trip fantastic due to the insight with train tickets, money belt, etc.. A few good ideas, get a Capital One credit card as you can use it there with NO fees whatsoever. For an ATM card, get an EVERBANK card (online application) as they charge no ATM fees either. Pack LIGHT (only take a backpack/rolling bag combo) and do your laundry every 4 days in the shower, you won't regret it.
London - 3 nights
Venice - 2 nights (MAGICAL)
Florence - 3 nights
Vernazza in Cinque Terre - 3 nights (most beautiful hiking trails)
Siena - 1 night
Cortona Tuscany - 2 nights
Umbria Orvieto - 2 nights (NOT TO BE MISSED)
Rome - 3 nights
Sorrento - 5 nights (day trip to Amalfi Coast, Capri, Naples and Pompei) - Amalfi Coast & Capri are not to be missed
Paris - 5 nights (day trip to Versailles)
Have fun!