I just took my 32 lb boy to his first trial, and used a 30" crate. After seeing him stuck in there all day, I'll definitely use the 36" in the future. So, I'd use your 36", you will not be hogging unnecessary space! What else to bring? The usual stuff you'd bring to class. Water, treats, poo bags. Make sure you have the right kind of collar (or no collar) and a leash that's easy to remove/put on. If it's allowed, food and drinks for you, of course (some places have a food vendor and ask for no outside food). A chair for you, jacket if it's cold inside, and a cover for the crate if he needs to be covered. Have lots of fun and don't worry. Things will not go perfectly, but as long as your dog has fun, it's ok. Your job at his first trial is to make it a good experience for him, period.