Which guidebook to bring

Make copies of appropriate section and load into your ipad.

Load Scanner Pro app on your Ipad and scan the copies of the pages you need.
https://itunes.apple.com/us/app/scanner-pro-scan-multipage/id333710667?mt=8
Or if you don't want to deal with technology, simply make regular paper photocopies of the pages that you need.
If you have an Ipad you can basically find all the info you need online once you are connected to wifi at your hotel. There are items that are useful to have on the go, even when you have no wifi connection. Those are guides to sights (museums, churches, etc.) which you want to have with you while you visit those sights so that you can get an explanation of what you are seeing. Those are the pages you should scan or photocopy. Don't bother making photocopies of suggested restaurants and hotels, you can do those searches online and in any case the best source for restaurant names is from the locals, not from foreign guidebooks. There are also guides to sights applications that you can download for free or a small amount.

Without an ipad, but we have our iphones. I will probably make copies of various pages. But the Rome pages in the big Italy book are many. Orvieto is not a problem. What about on-the-spot possible other side trips?

You can also buy separate chapters from Lonely Planet guides (as pdf documents) on their website if you only want certain sections of the book.

Rick's book is easy to pull apart. Break the spine, then you can ease out the pages or chapters you want and hold them together with a clip. A friend of mine takes hers to Kinkos to have them spiral bound, but I was fine with just the loose pages which sort of hold together anyway. I encourage you to also pull out the index. I did not and had trouble in Rome when I was wanting to look things up. I had to force myself to mess up a book like this the first time, then I realized if I were going back I would get a new edition anyway!

Guidebooks go out of date quickly, they are the only books I destroyed as I used them. It was hard at first. Now I use iBooks, and buy them as I need them. I also can use it to buy books I wouldn't want to carry, but might be interesting to read in a specific city (i.e. Dan Brown's Inferno on a rainy day in Florence, but I was wrong about that).

I am taking Rick's Venice book and then taking sections from the big Italy book to compliment that-- Rome, Orvieto, etc. Having worked in the book business for years, it's hard to fathom, but it does make sense, since I'm not going virtual right now with an ipad or such. Thank you all for your help!
laurel

Laurel, you will feel like a criminal when you first tear apart your guide book, but no one is going to report you to the librarian in the sky! You will be glad of the weight you save.

You can also kind of do the opposite and tear out the general areas you don't want such as southern Italy and the north. You can then peel off the spine along with the front or back cover then trim it to fit your new width book and glue it back together.