I just wanted to make a quick comment about the Wonderland Trail, since I have worked at Rainier since 2006... First off, don't be intimidated if you did not get a reservation. We do save roughly 30% of the sites for "first-come-first-serve." If you are flexible with your itinerary (starting point, dates, Keeping your party size under 6 people, direction, and mileage), we're pretty good at getting something to work out for you, if not the entire trip, then a big chunk of the trip.
I also want to clarify that if you are doing the Wonderland Trail you MUST stay in one of the designated sites (camping 1/2 mile off the trail is NOT permitted as indicated in the article) along the route in order to preserve this wonderful wilderness. With over 2,000 reservation requests received this season, you can imagine the havoc that could cause if we didn't have quotas in the park's wilderness management plan.
I hope this helps some folks in planning their trip.
This URL will also help in your planning process: