On a more personal note, you may want to bring along snacks to keep you going between meals and your favorite brand of pop in case the hotel or convention center only sells a brand that you don't drink. If you are not staying at the hotel that the Con is taking place, then you may want to check shuttle bus schedules to the Con so that you won't miss any important events or have trouble parking at the Con. If you are planning on wearing a costume or multiple costumes, it might be helpful to make a checklist of not only the clothing that you will need, but also the accessories and makeup.
More general tips that can apply to any vacation trip:
1. Make sure to pack underwear, socks, toiletries, and medication.
2. Make sure to pack items such as cameras and swimsuits.
3. Organize pet and/or child care well ahead of time and confirm well ahead of time.
4. Take out the garbage.
5. Make sure not to leave any clean, wet clothes in the washer.
6. Perhaps clean up your house a bit before leaving because it's always nice to come home to a clean home.
Speaking of which, back to the laundry!
I Write, I Edit, I Write Again. Witness!
We're Making Better Words, All of Them, Better Words.
I Write to Burn Off the Crazy.