I have run a site about how to make a personal webcam site that ranks high on google world wide..
I have never invested in promotions but rank very high on searches.. example search on bing
http://www.bing.com/search?q=how+to+make+a+webcam+page&qs=n&sk=&sc=1-23&form=QBRE
I rank 4th out of 1,680,000,000 results. Although the site is not driven to be a social site, just information. I get questions via the "contact" form mostly.

Another site, social one aimed at my city see more "Jacksonville FL" does well too, just by tweaking your site title to google searches.
Locals search the for "jacksonville video chat" and I'm 1st out of 3 million results.
https://www.google.com/#sclient=psy-ab&hl=en&safe=off&source=hp&q=Jacksonville+video+chat&pbx=1&oq=Jacksonville+video+chat&aq=f&aqi=&aql=1&gs_sm=e&gs_upl=14262l14805l7l15660l5l4l0l0l0l3l239l667l1.1.2l4l0&bav=on.2,or.r_gc.r_pw.r_cp.,cf.osb&fp=ec7fae886d32900d&biw=1280&bih=909
to me, its all in just a few words

I personally think the SEO for Dolphin is top notch.. Even my demo site ranks high on google.

So staying local or going global with Dolphin works perfect for me. It takes time.
Hope this is not misunderstood....