1. That it basically flies by so soak it all in, the expo, pre-race, the race & post-race stuff!
2. Hold out for real bathrooms on course if you can
To the real bathroom point Coach Charles way back in the day used to post where those real bathrooms are:
Based on running goofy a couple of times here's were I remember them during the half and full. Please comment if you know of other ones.
Half Marathon:
Before you start there is a real bathroom near the base of the monorail platform by guest relations
Mile 4 at the gift shop near the TTC. There are bathrooms at the back of the building (you pass on the left hand side of the building.) bathrooms are at the back of it past the vending machines. There are also bathrooms on the right hand side of the building. You'll have to go slightly of course to get to the bathrooms on the right hand side of the building but the lines there will be much shorter.
Magic Kingdom about mile 5.6 there are bathrooms in Tomorrowland. They are both by mickey's star traders. There are also the bathrooms to the right of the teacups.
In Frontierland around mile 6 there is the large set of bathrooms between frontierland and Adventureland.
Epcot around mile 12 there are bathrooms in the buildings near spaceship earth.
Full Marathon Bathrooms are the same through mile 6ish
Animal Kingdom about mile 12.5 there are bathrooms in asia right on the side of the course. This is one of my favorite bathrooms because it's so close to the course.
Studios about mile 23.25 as you make the turn to head down towards tower of terror there will be a bathroom on the left.
Epcot about mile 25.2 there are big bathrooms close to the course on your right just before you get to Germany.
I'm sure I'm missing some in WWOS and in AK studios and epcot.