Websites on The Wonderland Trail:
The elevation profile: Yes, this can cause crying…
Mt. Rainier NP: A quick bio of The Wonderland Trail.
Mt. Rainier NP: An in depth bio of The Wonderland Trail.
Mt. Rainier NP: The permit process.
Mt. Rainier NP: How to do food caches.
The News Tribune: Quick article on the trail.
Books & Maps:
Discovering the Wonders of the Wonderland Trail: Encircling Mount Rainier
Mt Rainier National Park Hiking Map and Guide
Trails Illustrated Mount Rainier National Park Trails Map: This is a highly durable waterproof topo map that shows the whole Wonderland Trail.
Green Trail Maps: The can be found in every REI and NP/FS station in Washington State. You will need #269 & #270. Map #270S is a blowup of the Paradise area, not needed unless you are heading off the Wonderland Trail.
Free Maps: While not what you want for trail use, these are good for planning.
The Wonderland Project