My terrarium has water at the bottom with an aerator for humidity, and no lid at all. It sits under the kitchen counter, and the lights are under-cabinet mounted. The plants sit in trays, on lifted platforms to get them closer to the lights above.
I refill the trays about once a week (depends on the size and depth of the tray) and have never had the water level at the bottom drop much. I end up pouring it out and scrubbing the tank clean of algae, and microwaving the platforms, trays, and weight-rocks in the bottom about once a month. *shrug*
The temps stay around 70, and the humidity about the same. So far so good.
On the other hand, the CPs NOT in the terrarium need watering daily to maintain their humidity level.