mosey,
It's good to know you're from Vancouver, as I'm quite familiar with travel from there. A few more questions....
- Which airline are you using?
- Does your return flight leave from Florence?
- Are you ending your trip in Florence, or going elsewhere?
- Are you planning to see Venice?
- Which part of London are you planning to stay?
For your stay in the Cinque Terre, I would recommend staying in Monterosso, as it provides the best atmosphere for strolling along the beach. It's the largest of the five towns and therefore has the best selection of restaurants, hotels and other tourist amenities. I would also highly recommend Hotel Villa Steno but one important note - BOOK EARLY as it's very popular! If you can't get a room there, try their sister property, Hotel Pasquale.
For your flight from Paris to Pisa, you might consider using an easyJet flight from ORY.
I'd suggest allocating extra days to Florence, as it makes a good "home base" location for taking day trips to other places in Tuscany such as Siena, Lucca, Pisa, etc.
As it's your first trip to Europe, you may find it really helpful to read Europe Through The Back Door prior to your trip, as it has a lot of good information about how to travel well in Europe. You should be able to find a copy at the Library. After that use the country or city-specific RS guidebooks to plan hotels, sightseeing, transportation, etc.
Especially for travel in Italy, there are some potentially expensive "caveats" to be aware of when using trains and other public transit. It will be easier to provide more details on that once you have a route mapped out.
I'd suggest leaving Spain for another trip, when you have more time to explore. If you want to explore another area, you could skip the flight from Paris, and instead travel by train to Switzerland and then Italy. It's "on the way" so easy to do. One point about Switzerland - the Berner Oberland especially is very scenic with cows grazing in alpine meadows with bells on their necks, quaint buildings and incredible mountain views. It's expensive though.