The problem you run into is the cost and overlap. Typically if you're creating an authority site you don't have to worry as much about being slapped. Age and trust take care of that.
I only go the multiple site route for 2 reasons: local keywords and buffer sites
Instead of wasting your time on multiple small sites just create a decent size site. Then use buffer sites with unique content, videos, and unique content pages from other sites that all point back to your main site.
Take those sites and pages and blast them. I actually try to rank them. I had 1 keyword with 40,000 searches a month that I ranked #1, 4, 5, 9, 11, 15 and many more through 100. They were all unique pages of content on other sites that I would target trying to rank the pages. I actually would get traffic from some of these pages.