As a Captain, a big part of your job is training your FOs! This may involve some occasional feedback/advice on basic stick and rudder stuff. But the majority of it is helping your FOs understand the system and how to operate with safety and efficiency.
Somebody posted a comment about how when it is time to go you go unless you are waiting for your clearance. What made you believe this? There are tons of things to consider and ensure are 100% correct before you ever think about heading out to the airplane. Have you ever noticed flight attendants telling people to sit down and ask you to pay attention to their pre takeoff safety briefing and insist you remain seated? The crew cannot push if passengers are out of their seats.
Do you have the right number of people on board? Do you have accurate weather? If not you have to get it. Do you have enough fuel? Are you going to have to leave bags, cargo, or people if you are overweight? Dispatch does a lot of this BUT they did so well before your flight. Weather may have changed, an earlier flight may have cancelled, thousands of things can and do happen every flight. And it is all on you to make sure everything is legal and safe. Remember, you can delegate performance but you as captain are always accountable. Remember, even commuters operate under 121. Under 121 many of the rules start out with wording along the lines that no carrier will assign AND no pilot will accept. Your employer can self disclose which means if they screw up (bad maintenance, not airworthy aircraft, dispatch negligence, etc.) they can self disclose to the FAA apologize and get off with no penalty while you wind up with a violation and possible loss of your license.
Hope this helps you understand more of what sitting in the left seat involves.
Jon