The strongest directories are the ones that actually have a review process, and don't just accept all links. It's not worth your time weeding through thousands of junk directories. Dan's pretty good at maintaining a quality list at http://info.vilesilencer.com, so if you're looking to submit to a bunch of directories it might be worth checking out.
You're right, Snowblind, A high PR of the frontpage doesn't help much. What really helps are user reviews and traffic quality. I built a do follow directory with many options when adding a website. Actually, a full list of features can be found here, in the directory review thread. So I aim two goals: help you with the PR "juice" and help users find your website easier. We only accept other DoFollow websites! Click for a DoFollow Portal with reviews, manually approved. Thanks!