To gather information for a trip, I do the following:
1) Go to the bookstore and look at all books that have information regarding my itinerary. If the RS one covers it, then I will get it.
2) Check out the tourism websites for the countries, cities or towns I'll be visiting as their information is up to date.
3) Check with my local library to see if they have any copies of the guidebooks that cover my itinerary. (With libraries online, I can do this from the comfort of my home, and if a book is available at a far away branch, have it sent to my local one for free. Easier to pick up.)
4) Go back to the bookstore with notebook in hand, gather up the guidebooks I have not yet checked, get a cup of coffee, and start taking notes.
5) Go online for any other information I might need/want. (This step can and is usually done earlier in the process>0
With this, I've covered everything and I'm prepared for my trip.
I've found that some things Rick says are a don't miss, I want to miss. As an example, he's religious and loves churches and cathedrals. I've seen the major ones and don't plan to visit any more. A guidebook's author's suggestions are just that, suggestions not gospel. (Well to most, some here I think have a shrine to RS in their homes. :) )