A couple comments:

1) Many hotels will guarantee your room for arrival (even if it's at three in the morning) if you you guarantee your reservation with a cc. I always look for this information and print it off.

2) If there's no such guarantee, I include in my email of the cc details an estimate of when I'm going to arrive but also a request to please hold the room for me if I'm later than that time, even if it's much later. And I print that email off and take it with me.

3) When I send a cc guarantee to a hotel, I always request that they send back a specific email confirmation that they received it, and print that off. If they don't send one, I keep after them until they do.