Just for a change we decided to go to a bookshop. Once inside I couldn't seem to find the will to walk our again, until hunger drove me to an adjacent coffee shop. I'd forgotten how wonderful it was to have a good browse with the physical objects (i.e.books) to hand. I was sorely tempted to buy a few more, but luckily remembered the towering TBR pile and managed to restrain myself. It was a near call though.
The top 10 guide is for the actual trip. The Granta City Guide contains some guided walks. The Art and Architecture guide provides some good background information and pictures on the sights. The Oxford Archeological Guide contains a lot more background information. The big rise and fall book is a pictorial history and gives a good overview.
How on earth I am going to get through all these before we go (and learn Italian, and do all the other things I need to do) I don't know, but I am going to have a go.