Just make sure it's not in a white pillowcase. Something to dry up a runny nose is also handy, especially for those with allergies. Earplugs - If you're going to be sharing a room, or are sensitive to every unfamiliar noise, a set of earplugs are going to make all the difference between getting a good night's sleep and killing off your room buddies. They can also help protect your hearing during some of the kon's noisier events. Clothing for a Change of Weather - Texas weather, even in June, can be amazingly changeable.
Rain can really drop the temperature to the point of shivering.
A sweat shirt can make all the difference. Camera and Film - You never know who you're going to run into around any corner. The folks back home are never going to believe you really met some fabulous guest, unless you have that picture to prove it. You're really going to burn through the calories with the busy pace of the kon, so midnight snack attacks are not uncommon. Even if you live in the area, having a room means you can party, game, watch videos or stalk through the Dealer's Room without losing time to commuting for food or sleep.