This looks like a good spot to plug the Thru-hiker's Handbook (available at
www.trailplace.com and many booksellers), so I will.
Here are its advantages, IMO:
It's concise. There isn't a lot of useless information, but it covers what you need to know.
It's up-to-date. I personally visited every trail town this past October, even the obscure ones. Places that were out of business have been taken out of the book. The book includes a number of new services.
It's easy to use. It's in the same format that Wingfoot has used the last few years, and the maps have been updated.
I don't claim to be unbiased.
(FWIW, LW's price comparison is misleading as shipping is included in the price of the
Handbook.)