Block above content should be simple however I have a site where they are wanting to have a block above various pages without having a ton of blocks on the blocks layout page. For example they want a block above the login form on the user login page with a welcome message and or instructions that they can easily edit. They also want another "description block" above other pages that we cannot easily add blocks to without giving them admin access such as editing views etc. Does anyone have suggestions as to a way for me to go? I originally thought of using page manager however page manager does not let you use the main content block within itself when you override the path of an existing page.
There is a number of Block related access modules that can help you: 

Block Access allows you to set individual Block permissions. So after you create those Blocks, allow the specific user Role to edit only those particular blocks above Login and other pages. 

You might also create a special Region within your theme just for this purpose, and set permissions for that Region blocks with Block Region Permissions. 

You can set finer control over the Admin Block pages with Block Content Permissions.