What do you always end up scrambling to finish before a convention?

I’m launching HallPass tomorrow, a free web and Android app for finding conventions and keeping trip plans, cosplay builds, budgets, and prep checklists together.

I’d like to hear from people who actually go to conventions: what do you always end up sorting out at the last minute? Is it packing, finishing a cosplay, budgeting, or figuring out where to stay and eat?

You can try HallPass at https://hallpass.me. If you give it a go, tell me which part helps and what your usual planning routine still handles better.