Sensirion SHT11

As it turns out, it is much more difficult to find an acceptable, low-cost humidity sensor.  I tried several sensors including the DHT11, DHT22, and AM2302 before deciding that none of them would work well. They weren't particularly accurate and they were extremely difficult to interface with. Eventually I broke down and decided to spend a little more on a better sensor.  The SHT line of sensors from Sensirion turned out to be fantastic. They are very accurate for both temperature and humidity (especially the higher-end ones), and with the help of a Python package that I found online (rpiSht1x - read more here), they are pretty easy to interface with via 2 GPIO pins.

SHT11 Breakout Board from Adafruit

I currently have the SHT11 which is the mid-level sensor that Sensirion offers.  I would like to upgrade to the SHT15 but it is more expensive and difficult to find as a breakout board.  If I can find it, I would like to buy the SHT75 which has leads attached to it from the factory.  Another option is to switch over to Sensirion's newer SHT2x series that communicates to the Pi via I2C (see Sensiron's lineup of humidity sensors at their website).  These other sensors would be great in the future, but the one I have will work just fine for now.