Just another thought on using the newer article directories: As I mentioned, even though they haven't been around that long, some of these directories get really impressive traffic. I believe that you can use this to your advantage by being mindful of people searching within the directory itself (as opposed to coming from outside, via Google and other search engines).
Say you're writing an article about a subject that is not saturated, but then isn't that obscure either. I'm building a new site that's about comedy - stand-up in particular. So that's a good example.
Now if I'm targeting the keyword phrase "stand-up comedy" in, say Ezine Articles, I'm up against a lot of other articles on the subject, many of which have been around for ages, and have even garnered a few backlinks themselves. So I almost certainly won't get anywhere near the top of the results for people doing a custom search of that particular directory.
Sure, I'll get some traffic for long tail searches. And it's still worth doing for a whole host of reasons. But I just won't get on page one for that primary keyword - which would obviously be the best one to get because of its frequency and relevance.
But if I try smaller directories, then it won't be too hard to achieve this goal at all. There are less people searching those directories, but then there is so much less competition as well.
Of course it'd be very very hard - if not impossible - to test this hunch. Very few article directories have comprehensive stats. And even if they do they don't say whether visits to your articles are from Google itself, or from searches within the directory. Still, it's something I think could work well.