I'd have to add Pet Sounds to my list. And I disagree a little with his point about Sgt. Pepper's. Maybe it doesn't stand up as well over time as some other Beatles albums, but, at least to me, it's only value is as an album. "(L)istening to a couple of favorite cuts on the radio now and then..." doesn't satisfy my Sgt. Pepper's jones. That need, which has, admittedly, dwindled considerably over the last decade, can only be met with the whole album. But that's just me.
Also, though I'm likely to get raked over for this one, I liked Elvis Costello's Juliet Letters*. Nowadays every act thinks it can make themselves serious artists if they hook with the Poughkeepsie Pops and put out a live version of a bad rock song with some confused bassoonists and second chair violin stand-ins. Elvis actually teamed up with a classical quartet to write an album of songs suited to the instruments involved, but melded his distinctly non-classical voice to create something very different. And it's as "conceptual" as you can get.
Go ahead and fire away, boys. If this doesn't bring out some heated argument, nothing will.
*Eno will no doubt point out that I'd think Costello warbling his grocery list into a soup can on a string would make a great concept album. I'm a fan. Guilty.