I've found that "what's your typical day like?" to be a good starting point. Pay attention to their answers, ask follow-up questions, and you're likely to get a

I've found that "what's your typical day like?" to be a good starting point. Pay attention to their answers, ask follow-up questions, and you're likely to get a good sense of the company culture and state. Generally speaking, you should be asking just as many questions as the interviewer, interviewing the company just as much as they're interviewing you.