Insurance Coverage - How to Determine

[Tony Castronovo]

How do you all determine how much to insure your properties for?  I've been using a general rule of thumb that considers the overall property appraised value less the land in the event I would have a total catastrophe and have to rebuild the entire home.  Not sure really how to determine replacement cost since the cost of materials and labor could be more or less than the current value of the structure.  Any rules of thumb or more formula-based approaches you use?