Hi Jeff,
First of all, as previously mentioned in another question of yours I would recommend redirecting from non-www to www or vice-versa. And after that using only one version of the URL to link to your website.
Now related to this question: I wouldn't bother myself with PR.
If working with directory listings I would go to the most popular ones from my business niche. For example here on SEOmoz we have a list of web directories which were recommended by mozzers: http://www.seomoz.org/directories
I would recommend you to read through the short text on that page, it will give you on overview where to submit your listing.
Greetings,
Istvan

