Gas-station bathrooms are a little like your dishwasher: You never know if what’s inside will be clean or dirty. So before hitting the road, arm yourself with printouts from The Bathroom Diaries (www.thebathroomdiaries.com), a guide to which roadside restrooms are stop-worthy and which are a no-go. Or order a free pamphlet on Arthur Frommer’s favorite public potties in 19 U.S. cities at www.wheretostopwheretogo.com.