Elly, we happen to prefer The Trailer Life Directory for its layout and coverage. We bought several Woodalls in the past and just couldn't get what "we" needed from them. Other people prefer Woodalls. I think they may both have the same owner now so it may be a moot question in the future. With the economic downturn we've had several campground owners and managers survey their customers wanting to know which directory people use because they had to cut one or the other advertising budget. Many people don't realize that none of the directories is all-inclusive because campground owners pay to have their entries in the directories. We've found some nice places that weren't in either one because they were small and advertising space was too expensive for them. We found those campgrounds through brochures at state visitor centers as we entered the state in which they were located.
Either directory has thousands of listings in every state, Canada, and Mexico so you need to look at a copy of each to see which one best suits your needs. By the way, I still prefer paper copies myself, especially when you're looking for campgrounds in an area where you could be in several states. For example, near Washington D.C. you have Virginia and Maryland. Near Pittsburgh you have Pennsylvania, West Virginia, Maryland, and Ohio. I like to be able to put markers at places in each state and go back and forth visually. Sometimes it requires a lot of juggling to get closest to where you want to go!
ArdraF