I think with the one I want to make a private membership I want the title of the post to be picked up by the SEs, but the actual meat & potatoes of the post to be private. Does either of the 2 you recommended do that?
As for the one I want totally removed from the net, you said we could set a specific landing page, but will using this plug-in remove all the posts/pages that are currently in the SEs, or do I have to remove them manually from Google which will take forever?
I built a WordPress powered membership site some time ago for a client that wanted what you asking for. This can be done using “excerpts” where the first paragraph, or what ever text you want, along with the title, will be exposed (to both public and search engines). I probably wouldn’t try exposing some content just for search engines and not for the public as this falls under the cloaking umbrella which will land you in hot water.
As for turning the other blog off. Any requests for the old pages will be returned with the landing page, so eventually (pretty quickly depending on the crawl/index rate of your site) will get consolidated with the landing page. You won’t have to remove them manually. There’s no way, other than a URL removal request to speed up the “de-indexing” process.