I've been to several large shows and discovered I need to plan ahead. The first thing I do is peruse the catalog and learn about everything that is going to be happening at that particular show - classes, demos, lectures, quilt displays, special exhibits, vendors, how the classes are priced, etc.
Then I take 1 sheet of paper for each day I plan on attending, go through the class list and write down which classes (including times) I'm very interested in taking. On the list for each day, I also write down other activities I want to do - demos, lectures, lunch etc. Next I whittle the lists down to a reasonable (for me) schedule and budget. Some classes have additional supply fees. I leave a chunk of time to view the quilt displays and shop the vendors on one or more days.
Also, I create a shopping list containing items needed for UFO's, current and future projects.
Bottom line - plan, allow serendipity and ENJOY!