Not very many RV reference books, but have collected more than a few dozen travel books, for U.S. and overseas. I don't use them for planning, rather for ideas about where to go next. I also collect books on my travels.
Magazines too. For a long time, we got National Geographic Traveler, Budget Travel, Motorhome Magazine. I still get Home and Away from the auto club. Read them, toss them, let the ideas churn around in my head.
One reference, the Motor Carrier's Road Atlas, to stay out of trouble with a large vehicle. Then when going off the designated trucking roads, I ask locally.
Another, specific to one route frequently traveled, the EZ66 Guide for Travelers (though I have a few other Route 66 books). Also have one for the Lincoln Highway.
My favorite book for road trip ideas has been "Road Trip USA." This describes six north-south cross country routes, five east-west. Bedtime reading, from time to time, so I dream trips.
Looking at the top of the chest next to me I the Discovery Channel Guide to the American Southwest, Essential Guide to Black Canyon, RV Vacations for Dummies (several trip ideas), Adventure Guide to Oklahoma, Tony Hillerman's Navajoland, Scenic Driving Texas, Native Roads, Adventure Guide to the Alaska Highway, Roadside History of Oklahoma, National Geographic's Scenic Highways and Byways, Eccentric America, Roadfood, Watch It Made in the USA, Sierra Club's Pacific Northwest, National Geographic's Complete National Parks of the United States, Worlds Best Cities, AA Book of British Towns, Weird Texas, Readers Digest Most Scenic Drives in America and their See the USA the Easy Way, and National Geographic's Drives of a Lifetime.
More travel books are shelved and stacked up in other rooms. Not for reference (though some are take-along like the EZ66 and Road Trip) but mostly for ideas. I do put together a plan of sorts for each trip, so the trip fits a time frame, and we can figure out what we have time to see, what we might have to pass up.
A lot of trips are to specific destinations at specific times, so I might plan for two days, three days, four days on a frequently made 1100 mile diagonal trip, take different routes each time, allowing a extra half day (or two) for stops along the way. A lot of times the route will change along the way, a lot of different highways in the middle of this country will get you to the same place in about the same amount of time.
If you don't have a time frame, you don't need a plan at all. You just wander. But you still need an idea of what is out there that might be interesting to you. For me, that's why I have all the books, but your public library likely also has a travel section.
If you like crowds, get one of the "bucket list" books and go to the places everybody else has been told they must see before they die.
