So are you kind of saying that industry decides what fields you'll be focusing on? There are industries for plenty of fields, but many companies probably cover multiple fields at once, right?
I say I'm "not sure what field I'd be interested in" mostly because the Chemistry department here at school urges us to specialize in an area. I haven't gotten much of a chance to do that, but still, I'm wondering if getting a range of areas covered will work as well, better, or worse.
The notion of a "field" is kind of ambiguous, unless you're doing organic synthesis. You're correct in thinking that most jobs, and research, involve a mixture of things. The subdivision of chemistry, and indeed all of science, into categories like "inorganic," "biochemistry," "physical," etc. is mostly artificial, and any innovative work is going to combine aspects of several of your chemistry courses.
For example, I worked as a chemist in the soaps and detergents industry for a year. Mostly this involved acid/base chemistry, such as tweaking the pH of different things, making different combinations of detergents to increase cleaning power, etc., but it also involved spectroscopy, rheology, and statistical analysis. As another example, my current research combines aspects of optics, inorganic chemistry, materials science, and nanotechnology. That's really how innovation happens -- by combining different aspects of a wide variety of topics to produce something new.
IMO that's one reason why it's important to start reading the journals early in your chemistry career. The classroom is often too academic to give you a sense of how what you're learning will be applied to real-life research. Reading journals will also help you decide on the focus of your major, because as you are exposed to real research, you can find new things that you truly find interesting.