A very very long time ago when I was less experienced and in the days of the green I-94 I was arriving into LAX from LHR and was meeting a colleague at the Avis desk who had flown in from PIT. He had all the hotel details and I did not. I left the hotel information field blank and proceeded to CBP where I was promptly turned away. I was approached by a helpful CBP lady who wrote in an address that meant nothing to me. I was duly cleared and headed on my way to the car rental desk.