You can also ask them to charge over the amount that you have on your room charge and reauthorize the original amount again.
values - $500
moderates - $1000
deluxes - $1500
We always to this the night before we leave. This way we can check it at night and just look at the one on our door quickly the next morning. I would rather deal with an error in the evening than the mornnig.
I also just write the charges down each night and keep a running total.