When I've been asked if I have any questions at the end of the interview, I usually ask, "If I were hired for this role, what would be the first task you would want me to accomplish?"
Sometimes the interviewer talks a lot about the role itself and the actual tasks involved. In that case, I might say something to the effect of, "You've explained a lot about the role and I feel confident that my skills and experience would be a good fit for the task. Since we spend so much of our time at the office, can you tell me a little bit about the office culture here at XYZ Company? How would you describe the office 'personality'?"
Of course, I kind of have to go with what CarolinaDG said earlier. If the interviewer(s) cover everything you could have possibly asked, then I would just go ahead, be honest, and say something like what CarolinaDG suggested: "Wow, I had all of these questions about the company and you guys did such a thorough job, you answered them all! Thank you so much for anticipating my questions!"
.....Kelly
