Buy the ticket, take the ride.
There's nothing worse than going on a trip, getting halfway to your destination, and then realizing you left something essential back at your domicile. It sucks balls to say the least. Now, this may come as a shock to some of you, but yours truly used to be a Boy Scout. Okay, I'll admit, not a very good one. But I took the “Be Prepared” motto to heart and as such I tend to be ready for most occasions. Now I'm passing along my tips for easy and compact travelling along to you in the hope that you will have the best time possible at PAX (or ComicCon, E3, Quakecon, etc…).
The Essentials – These are things that should be mandatory for you to bring not matter who you are. Do not travel without these. Not just for your sake but the sake of those around you.
Tickets: This goes for passes, plane tickets, and train boarding passes. To make sure you won't forget them, put them in your shoe or right below your house keys the night before you leave. It's the best way to make sure you have them in hand.
Extra room in your luggage: You're going to a convention, so let there be no doubt in your mind that you will end up with more swag either for yourself, your friends, or your loyal followers who you know what to do with, so make sure you have enough space to get it all back. I use a U.S. military surplus duffle bag to get around when I'm on the road. They're cheap (about $25 max) and made to be durable. Usually I can fit all my gear into one and still have over half a bag left to fill up.
A day bag: No matter what you're doing you're going to have to keep your stuff somewhere while traversing the show floor. A smaller backpack or messenger bag will usually do the trick.
Toothbrush, toothpaste, dental floss, breathmints: Hygiene is important. The hotel or the friend whose couch you're staying on will usually provide towels, shampoo, conditioner, and q-tips, but the rest is up to you. Keep the mints or some gum on you throughout the day to freshen up after ingesting horrible convention food, like chili cheese fries or onion rings.
Deodorant: Yeah, I could've lumped this in with the oral stuff, but Jesus Tap-Dancing Christ on a Pogo Stick, do you ****ing nerds smell! I don't know what it is, but for some reason a majority of you think it's totally cool to not use this junk. NO! Put it on right ****ing now, goddammit! No one wants to smell your dungeon ass stank! NO ONE! Do this not only for yourself, but for everyone else attending the expo or elsewhere.
Sunscreen: I've driven up and down California more times than I can count and this is a MUST for traveling by car. You do not want to go through an entire con with a half-tan. Unless it goes with your cosplay outfit. In that case, enjoy the malignant melanoma.
Reading Material: For most of us, it takes a long time to get from where we live to where the action is taking place. A good book is the perfect way to kill time while in transit. As long as you're not behind the wheel. And don't be afraid to bring a stack of comics to share with everyone else you're pulling a Kerouac with. My recent travel reads include Slaughterhouse Five, Badass: A History of Badasses, Marvel's Earth X trilogy (very, very long graphic novels reallllly good for a loooong trip), various Batman trades, and I always keep a copy of Geek Love around just in case.
A laptop: Face facts. You're a nerd, do you really think you're gonna last long without the Internet? No matter what you're there for, business or pleasure, you're going to need it. At very least to check up on GR each day, right? I recommend a tiny, barebones Acer or Eee PC. They're inexpensive and small enough to fit in your day bag, just in case you need to live blog running into Will Wheaton on the show floor or update your Facebook with kittycat smiley faces and hearts.
Nerdy clothes: Nothing says “CONVENTIONEER!” more than a shirt with something nerdy or clever. I usually buy my T-shirts through shirt.woot.com. They're only $10, unless you want to pay an extra $5 to get it overnight. Their T-shirts are also only sold for one day long, which limits the odds that you'll run into someone else wearing them. Threadless is another great source for geek chic, but tends to be cost more.
Depending on the weather a jacket may be necessary. I go with my Ghostbusters windbreaker when appropriate; otherwise, I rock the standard black ninja suit hoodie. Jinx has a nice line of coats for the discerning fashion nerd if you want something a bit more high-end.
A stylish lanyard for your badge is a nice touch, too. I go with the Pac-Manyard I got at E3 2010, because nothing is more pimp than Pac-Man.
A camera: Why would you not a bring one of these? Sure, your iPhone can take okay pics, but wouldn't you rather have something decent? It just makes sense to have one on you at all times because otherwise you're bound to see something epic, try to explain how awesome it was to your friends, only to have them call you a liar and more than likely beat you up to cover up their jealousy.
Cash Money: Most places will take your plastic, but some won't and almost all of them don't haggle with credit cards. Pay in cash as much as you can and you can probably work your way into a better deal. Make sure you carry your cash somewhere safe, though. Not everyone is honest and folks do get their wallets taken either on the show floor or on the streets. There are many travel wallet options out there, but between you and me, this is the one thing I've never followed my own advice on. Mostly because I like to live dangerously to the max! I am so on the edge!
Bonus Round for Journalists (and future Journalists)
This for all of you who are going to be working or are just making sure you've got the most up-to-date coverage. The frantic pace of any event can be overwhelming even for the most experienced press man. Here's a list of a few things that will make things run smoother for you:
Smartphone: I don't care if it's an iWhateverthefuck or a new wave Droid; these things make your life a lot easier when you're out and about on your feet and need to make a quick post. Facebook, Twitter, e-mail and your website, all at the touch of your fingers. Be prepared to experience the worst lag in your life on your connection, though, as most Cons turn into dead zones quickly.
Hand-held voice recorder: I use a ZOOM H2 handy recorder, but there's a newer H4 I recommend as well. If you're a podcaster, these are a must-have, but they're also great for impromptu conversations and taking notes at Q&A's or panels. And you can track the progress of your Aaron Neville impression too.
Whiskey: This one should be the most obvious of all the accessories mentioned so far. Every great writer needs an equally great drinking problem. Duke has his homemade beer, Chris loves his vodka and Clamato, Nick has his Wild Turkey bourbon, and I love me a fine Irish whiskey or some jack and coke. Go to a liquor store near your hotel and grab a bottle for the trip. Hide it in a plastic flask if you have to.