Soot and Stars
I AM SOOT!
I've just noticed Soot and I have both used the word gibberish in the context of concept albums.
Two of the best "concept albums" IMO are APP's Tales of Mystery and Imagination and The Turn of a Friendly Card.
I don't think either one are APP's best work. That title goes to iRobot. However, these two albums are probably the best examples of tight concepts that you can actually hear when you listen to the songs in order as they were meant to be heard.
Big Ears, it sounds like that word is just naturally synonymous with the genre! BTW, I like the one album I own from Ayreon but once again it's musical and I have no interest in the subject matter. Usually a large number of these concept albums become apocalyptic for some reason!
Aero, I like the Alan Parsons sound. I like the first album you listed. I found it in LG's thread years ago. I own the second one you listed as we. I don't know what they are singing about but it's a very relaxing band to listen to.