I've never taken my dog into a building as it would just be one more thing to worry about and worried about what she would step in/on. But, she has been on a lot of reconnaissance trips. Sadly, my copilot tends to fall asleep shortly after takeoff.
Most recently to check out a large abandoned military complex way off the beaten path. As long as I am not busting any FAR's, I can circle overhead and form a plan all I want. It's not trespassing if I'm in the air.