Ideal optimization approach for 3x domain "ring"

[darkhorse]

Hello, all. With the recent shake-up at Google I am currently re-evaluating our SEO and would very much appreciate any comments/suggestions on the following.

Currently, we have 3 sites up but only the original URL is fully developed and optimized for ranking. The other 2 do generate some rank/traffic, but only about 1/10 that of the main site. Content is very similar w/ some "mirror" content that has been "shaken up" around 10% to avoid penalty. These 2 sub sites link back extensively to the main URL. One is hosted on the same server, one is not.

My question is this; how should I go about best optimizing this small ring of 3 sites so that they each compliment/support each other ranking wise with the top priority being to help the main site?

I should mention that strong consideration is being given to dumping the current content on the two subs and developing truly unique content on them.

Many thanks for your help!

[JamesR]

Yeah, do unique content and theme or niche them to a particular set of keywords and cross link between domains using keywords in your text links. Make sure you are linked to and link out to other sites that aren't your own. Your subsites can be powerful addition to your main site.

[mburgess]

What recent shake-up at Google?

[agerhart]

the recent change in their algorithm and mix up of their results