Problem: The air is stuffy, dry, and completely over-deodorized.
If you can, open the window—you'll sleep better in fresh air, Breus advises. If the windows are sealed (or if you're in a particularly noisy or polluted city), turn on the fan on the air-conditioning unit as soon as you enter the room to get the air circulating. Then add moisture by running a hot, steamy shower and leaving the bathroom door open.
Problem: The walls are incredibly thin—you can hear everything.
Book a corner room on a high floor, so you'll be farther from street noise and less likely to have two bothersome neighbors. But if you end up near a high-volume-TV lover, bring a small white noise machine or earplugs (with a noise-level rating of 32 or less, so you can hear your alarm and the smoke alarm). Or put white noise on your iPod.