(Ahem... sorry... apparently this is really, really long... I got on a roll 
)
I've used a little bit of everything, most of which have been mentioned before... Dreamweaver (in developer/code mode only) at work, TextMate for freelance (I have a Mac) and Notepad++ when neither at home nor work, on a PC.
Summarizing what I understand you to have said, you're looking for basically something that will allow you to get a site up quickly and effectively, while still allowing you to learn how to create a "brochure type" website that will look good and work for your prospective clients. In that case, a tool like SquareSpace might be your best option.
That being said, it's really important to consider what your primary goal is. Is it to learn how to build a site, or is it to have a great business website? While the two aren't mutually exclusive, it can be hard to get both if you aren't experienced as a web developer / designer.
If learning is important to you, then take the time to learn how to do it right -- meaning going code mode all the way, no WYSIWYG tools, no site building helpers. Your site won't be up right away, but you'll have gained a boatload of skills.
If getting the site up and functional is more important, then focus more on things like SquareSpace which will do a lot of the heavy lifting for you, allowing you to move more quickly. You won't gain the skills to do much of the work on your own, but then again -- web development doesn't sound like it's your business anyway
On a side note, there are a couple of other things I'd suggest any business owner should consider before building (or commissioning) a website.
An effective website won't be created by just jumping in and starting building. Really, a site that works and looks good is only the tip of the iceberg. Great sites have all kinds of behind the scenes work that go into them before the design and building even begins.
From doing some research into what your customers (present and future!) expect from your website, to things like figuring out what your content will be, how it will be structured, and how that structure will be supported by the design and the coding.
But like I said, the extent to which you want to go into those things are really going to depend on your primary goal is -- to learn to build, or to have a business website. That should probably be the biggest consideration when it comes to deciding tools you will use, and how you'll go about it.