A month or two after we take our air conditioner out of the window and into the basement for storage, we unpack our humidifer from the closet, thoroughly clean it out and set it up in our bedroom. We've had our humidifier set up since mid November and it will likely stay through March and possibly longer. (but fingers crossed for a real Spring this year!)
It is one of those things that I don't necessarily notice if we don't set it up right away in the cold months but after a few nights of using it and then sleeping one night without it ('cause I was too lazy to fill the tank), I definitely noticed! The next morning my throat was sore from dryness, my voice a little raspy and my nose actually seemed to hurt from the dry air. I now make it a point to make sure our humidifier tank is full before retiring to bed.
We have the AOS 7142 Digital Warm & Cool Mist Ultrasonic by Air-O-Swiss and it works great. It humidifies the air in rooms up to 860 square feet (80m2). It is pretty quiet except for the occasional gurgling noise and the tank holds enough water to last all night and then some. You can preset the humidity level you desire in your room and it automatically senses when the desired level is reached and shuts on or off to keep it that way.
We received ours as a Christmas present in 2008 — they cost approximately $210.
I chose the next 4 humidifiers based on the top reviews from consumersearch.com For more information on what to look for in a humidifier, Consumer Research also has this very helpful page.
Kenmore 15408 Est. $110
• Reasonably priced
• Humidifies a large 1,700-square-foot area
• Better than average durability
• Double-fill water tank
Honeywell HCM-630 Est. $50
• Compact size
• Dishwasher safe base
Honeywell HWM-450 Est. $65
• Compact size
• Can raise room temperature
• Digital controls
• Replaceable mineral pads
Air-O-Swiss Ultrasonic 7135 Est. $150
• Near-silent operation
• Hygrometer, LCD readout and antimicrobial silver stick
• Low maintenance