Conversion 4 Free sites vs. TGP galleries

Hello everyone,
I just got started with my first free site.

I was wondering if anyone could share their experience with free sites vs. TGP traffic as far as conversion goes... I tend to think building free sites is more of a long-term thing than TGPs. Links are more "permanent", and you're less likely to suffer from duplicate content penalties from search engines (that's just my opinion). You also tend to keep the surfer on your pages longer than with TGPs... And instead of spending hours submitting to hundreds of TGP directories, you can just submit to a dozen quality directories. I know you won't get the avalanche of traffic you get from TGPs but if you submit quality stuff over time, your traffic should build up and grow steadily... (right???)

My goal is to build lots of free sites like these and submit to a list of quality directories. Just have to rotate the recips links to make sure they fit the niche. It all takes time though, which is scarce...

So, as far as productivity and ROI, what do you think is best? Running free sites or TGPs? Or do you do both?

By the way, if you own a quality free directory, I'm interested in adding you to my list. Please let me know by posting here.

Thanks