Lets stick with guide line 1: No hectic, No rushing.
If romance is a fundamental part of the equation, then eliminate Rome, Pisa, Cinque Terre, and Pompeii.
Start in Florence. Bring a full sized lock and key for the Ponti Vecchio. On the first evening with your love, walk to the middle of the bridge, tell your woman that you love her, place your lock on the iron bar, or thru other locks, on the north-east side of the middle open section, then throw the ONLY key that opens that lock in to the Arno. Its okay to do this - its a tradition. Act with NO hesitation. Your wife will remember this moment forever. Walk to the Michaelangelo Over Look on the other side of the river and witness the sunset over Florence. Bring wine and make a toast to your new lives together. Make a day trip to Lucca and rent bicycles to ride the top of the city walls. Bring a picnic... ie more wine. Back to Florence.
Rent a car or motorcycle, and drive the 222 down to Siena, where you will over night. Walk the streets in the evening and the rampart walls. Take part in the evening Passeggiata. Dress well and walk slowly arm in arm. You are showing off your bride.
In the morning continue South and do the a grand circle of the hill towns, returning to Siena.
Head back to Florence, and do what ever you want for three days. Climb Giotto's tower. Go to the Ruins at Fiesole.
Then take the train to Venice, which will stop in Milan. In Milan see the Duomo and its roof top. Continue to Venice.
I prefer the west end of the Grand Canal. Aside from the major sites, it is actually VERY FUN to get lost in Venice. Every new corner you turn upon is a whole new section of the city. It is cheesy, but rent a gondola: at night. Even if it is expensive. Tell the Gondolier he has the most magnificent boat in all of Venice. Take a water taxi to the Airport. Then fly out of Venice. Gustare!