Multisite with some shared content and some different content
You don't really want a multi-site at all by the sounds of it. You're looking for Domain Access


  The Domain Access project is a suite of modules that provide tools for
  running a group of affiliated sites from one Drupal installation and a
  single shared database. The module allows you to share users, content,
  and configurations across a group of sites such as:
  
  
  example.com
  one.example.com
  two.example.com
  my.example.com
  thisexample.com &lt;-- can use any domain string
  example.com:3000 &lt;-- treats non-standard ports as unique
  


In fact, the ORIGINAL use case for Domain Access was for magazine sites (from the documentation), so it should fit your needs perfectly!