During my family's recent travels to the Canadian Rockies, we relied mainly on two books, the Moon Handbook and the Dummies Guide to the region.
The former was more comprehensive and knowledgable than the latter, which took an overly liberal scattershot approach to the region -- even for dummies.
But both had the dubious distinction of having information -- particularly about pricing -- that was wildly out of date.
Of course, that is par for the course for most guidebooks. The Moon book was published in 2005, for example, which meant that most of the information was revised and verified (hopefully) in 2004. When both books tell you that a Canadian parks family pass costs $89 CAD, but you wind up shelling out $123.50, it's a bit of shock to the system.
However, the Moonies and Dummies and their ilk can't be faulted if prices change, roads close and attractions go up in flames after they go to press. Nonetheless, in this age of instant information, it shouldn't be so hard for the publishers to attempt to update some of the most salient info on their Web sites at least once a year.
Moon has a good overview of its Canadian Rockies book on its site, but with prices from the outdated book. This is especially important when Moon and Lonely Planet, its main competitor, may go 2-4 years between editions on its titles.
This is just the task to sic a few interns on, not to mention the guidebook authors. To show how it could be done, Wizard Publications, the small publisher of four excellent Hawaii guidebooks, has an update page for each of their refreshingly honest and spot-on titles. "We are the only publisher who updates our books every time we reprint them," they boast. But when that's not possible, they turn to the Internet between editions, such as the latest one for the Ultimate Kauai book. No surprises, just a lot of aloha.