Review on 4PCS Geekstory DHT22 AM2302 Digital Temperature Humidity Sensor Module - Monitor Temperature and Humidity Levels, Perfect Replacement for SHT11 SHT15, Ideal for Arduino Raspberry Pi by Monty Barganier

These are good sensors to start with. There are no problems with addressing as they don't use I2C - just GPIO. The only issue I had was that if you need a longer cable it tends to fizzle out and not work very reliably. Otherwise they are fairly accurate and reliable. I wouldn't update the sensor data more than once every few seconds (I did it once a minute) because it'll annoy you, but it works damn well.