At least, hold onto your property in CA, so you can come back if you aren't happy in TN.Not only will the weather suck - really humid in summer, icy and cold in winter, but the culture is completely different.  

Risk of leakage, breakage, humidity, etc...  

If you install hardwood floors during less-humid months, their moisture content is pretty low.

I know we don't have that many days of heat in the summer, but the humidity makes it very miserable to sleep at night and they have kids.If they we not good tenants, I would not even consider A/C or extending the lease.

The hole was caused by an arc fault when one of the electrical conductor broke loose from the wire nut - hot and humid weather in Florida over the years the solid conductor got corroded. 

Redding is in a beautiful area, has god-awful hot summers (but not humid), but mild winters, and believe it or not, the property isn't horribly expensive in that area of CA.  

The black mold is due to too much humidity... are you using the bathroom vent when taking hot/long showers?

As you know humidity in South Florida is high, especially during summer months.

They find that the water on the ceiling was either due to the moisture/humidity from taking a shower or from just water splashing.  

That is bad for the house (humidity) and bad for the A/C unit to run that hard.Was it worth it from a cost standpoint...no.