Ben,
I use a Bemis DP3 200 humidifier/air purifier, it will humidify 750 sq.
feet. I do use R/O water in it so I don't have to clean the wicks. It is
a "cool mist humidifier nothing special.
A fan or fans should be used for air circulation.
Never measured the humidity levels feels semi-tropical, plants adapt.

Alan

Blue Mountain Bonsai
Ontario, Canada
Zone 6