Make them have to do certain side missions to get the scoop on the mansion security. The mage in charge of astral security leaves his notes out and everyone knows it, so they have to get them. A spider on staff will give details, maybe help, if they get his wife a rare expensive medicine. One of the housemaids is banging the maintenance guy and they'll give them HVAC blueprints if they make her husband disappear. Stuff like that.
My personal favorite is going through the mechanic. Rich folks love their cars/drones/autogyroes, and maybe some piece of legwork data was left in one that had to be sent to custom shop way out of the characters' usual area of operations.