Enough to break even. That is on the loss of property. My policy is for 80% of rebuild cost. I want less but no company will sell me less.
Enough to not lose your personal assets in the event of a liability claim. That depends on you. Shop around for best rates and coverage. It usually cost very little to boost your coverage to the next level (same for full coverage auto). I have $500,00 liability. I don't have an umbrella policy because it is less expensive for me to cover two houses separately.