Any of thirty different things depending on the situation. Amazing sunset tonight. Traffic is really bad today, Raining hard out there tonight. You travel to Seattle often? How long are you in town for? Heading home?When they say "Im fine, thank you for asking" and dont ask you how you are doing......what do you say next?
The options are so varied I could go on for years. Some times you do get a quiet vibe, and rarely I get a client ask for quiet.