We should start a fan-swapping thread like the stroller swap.
Our whole family sleeps with a fan and I always bring a small but really noisy one wherever we go. I've tried the white noise ones and they just don't do it for me.
I've tried this before: Set up your tape recorder and tape the fan noise for a few hours. Or if you can record straight to mp3 that's even better. Make a CD out of the noise and take the CD with you. If you just need the noise and not the air circulation, this is pretty good substitute. Unfortunately for me, DH likes the air circulation on his face so we have to bring the fan.