Well, my usual policy is to steer clear of debates about religion, politics and operating systems, but for once I'm going to make an exception -- I suspect I will be sorry -- because this discussion touches on my only real area of expertise. (I'm a software geek who has designed a number of large institutional network computing environments.) So here's a suggestion about directory and file-naming conventions:
Plan for Platform-Independence.
I personally use date-location directory names, leave individual image file names alone, and impose a logical organizational structure on top of the physical directory structure by using Lightroom keywords and Smart Collections. But that's just me.
However, planning for platform-independence when choosing directory and file name conventions is an objectively smart thing to do.
Before I licensed the more expensive Adobe image suite, including Photoshop and Lightroom, I did most of my post-processing with consumer-grade proprietary products (e.g., Photoshop Elements) on Microsoft Windows and open-source software (e.g., The GIMP) on an industrial-strength variant of UNIX, both of which I ran on inexpensive personal computer hardware. I hauled a MacBook Pro around when I was traveling, however, because it combined the best of both platforms: it had the ability to run most commercial applications on a clean, stable operating system and filesystem.
When I was ready to pop for Photoshop and, later, Lightroom, I had to make a decision. I wasn't about to pay to license them on both OS X and Windows, so I decided to migrate most of my photography to a Mac. But not all. I still scan film on Windows. I still run custom "shell scripts" to automate some metadata manipulations on standard UNIX. And I use network-attached storage devices -- both old PCs running industrial UNIX as well as a couple of small filing appliances built on Linux -- to store and back-up all my files locally before I push last-resort back-ups into the cloud.
I'm not doing all this because I enjoy fiddling with different computing environments -- okay, maybe a little -- but because the combination of platforms provides an almost ideal balance among cost, functionality and reliability. The hardware to run the Windows and mainstream UNIX machines is really inexpensive. (Whenever I upgrade my only Windows box, I repurpose the hardware into a UNIX server and donate the oldest UNIX box to whoever will take it.) I pay the "Apple tax" for most photographic work because OS X is a very pleasant environment in which to run applications. I have access to my UNIX-based repository of files from any of the platforms, as well as from my iPad and iPhone -- same would be true if I had an Android or a Windows tablet and cellphone -- and I am able to move fairly seamlessly from one desktop machine to another with an inexpensive KVM switch.
I'm not proposing that anybody do what I am doing. Others may do fine with a single operating system for the time being. What I am suggesting is that it's not a good idea to box yourself in for the future by using directory or file names that don't work equally well across different filesystems and filing protocols. However strongly bonded you are to your Mac or PC, the day may come when there is something you want to do that you can do better on a different platform.
UNIX has no problem with spaces -- Apple's OS X is just a variant of Berkeley UNIX, by the way -- but the standard UNIX "shells" (command interpreters) use them as delimiters, so it's best to avoid them. As several others have pointed out, you can make long directory or file names readable by using a combination of upper- and lower-case letters, or by inserting dashes or underscores, all of which are perfectly acceptable on any modern operating system. Backslashes are used as filing-component delimiters on Windows and as a shell "escape character" on UNIX and Linux, and slashes ("forward slashes) are used as filing-component delimiters on UNIX and Linux, so you should avoid them if you want to maintain platform-independence. Some other universal ASCII and Latin-1 characters take on special meanings on various operating systems in particular contexts, so it's a good idea to avoid brackets, parentheses, quotation marks, and colons and semi-colons, as well. And if you're in a country where your keyboard allows you to type a superset of Latin-1, you may be better off avoiding those special characters. It's still a somewhat Anglocentric industry -- although that is changing. (Does anybody know whether Adobe's products can handle file names in, say, Chinese or Arabic?)
Finally, it's probably best to assume case-dependence. While OS X and Windows are perfectly happy interpreting names in a case-independent way if you configure them to do so, UNIX and Linux really want to assume that upper and lower case letters are different.
These aren't really difficult restrictions to abide by. There isn't much information you might possibly want to convey in a directory or file name that can't be provided with letters of both cases, numbers, dashes and underscores. Lightroom has very powerful and adaptable organizing tools. And the nice thing about interacting with a database instead of a filesystem is that it's really easy to redo an initial organizational scheme that turns out to be unproductive if you later decide you made the wrong decision. It's a lot more difficult if you need to rename thousands of directories and files after the fact. Really. I've had to do it. More than once.