incrediBILL - 7:36 am on Jul 23, 2013 (gmt 0)
Building a site for 'link juice' is silly, build it for the 3 distinctly different audiences and if it's quality it will rank as 3 stand alone sites. For instance, If you had a site catering food and selling shoes it would be a big old mess all mixed together. I wouldn't mix them unless they're related, but that's just me.
If you split them up your 301 redirects to the new sites would pass the PR along.
I have a bunch of sites and getting a PR3/4 isn't hard, 5+ takes a little more work.
Imagine customising, updating and tweaking a blog and then repeating it all on two other blogs.
If they use the same layout you would only update one common staging copy and then deploy it on all 3 blogs, not hard at all.
If they are going to have 3 totally different topics, I'd host them on 3 different blogs.