The whole idea of these meetings is to discuss pretty much anything that's affecting your ability to do your work, so there's no agenda by definition. If something is affecting your work then it is affecting the business. Plus, a happy employee is a productive employee :)
So make a list of the things at work that are affecting your ability to do your job and start discussing those. Start with the most serious one. You won't get to discuss the one's at the bottom, but don't worry, they'll rise to the top of the list if they're serious enough or solve themselves if they're not.
Make a new list each week.
Some would argue that there's no point in discussing the state of public transport as your manager can't change that, but if it means that you're struggling to get into work then your boss does need to know. You could agree to slightly different working hours, or working from home one day a week (for example). The end result is that you are happier and hopefully more productive.
Being happier means you are more likely to stay with the company - your boss doesn't really want the cost and hassle of hiring your replacement, being more productive is better for the company's profits.