Who are the "smartest" musicians of the past 40 years?

This is a question which is rhetorical within reason. My definition of "smart" refers to those musicians who are well past their "use-by date", however they remain as visable/ relevant as when they were at the peak of their craft. It could be a unique combination of individuality and canny career management, or other unexplained factors.

My 2 nominations for the "smartest" musicians of the past 40 years are:

Elton John - whilst Mr Dwight has consistently released new material over the past 4 decades, in my opinion he peaked circa 1980. If you closely analyse his career management, Elton regularly aligns himself with "the latest thing" in music in order to keep his name in lights. From as far back as 1985 [duets with George Michael, when Michael was at his peak with Wham!] to recent collaborations with The Scissor Sisters, Elton will always be spoken about in the current music media. A very smart operator...

Madonna - when I turned 13, "Like A Virgin" was at the top of the pop charts. 25 years later, she remains extremely visable in the pop media. Recent duets with Justin Timberlake & celebrity divorces/ adoptions are the primary reason for Madonna's name to be known worldwide by all ages. It is apparent that she will vicariously use her daughter's increasing public profile to stay in the limelight. Whilst Madonna continues to release new music, she is essentially doing what she has always done; changing her image for each new CD release. Quite possibly the smartest player in the music business EVER!!!

I'm keen to read your opinions for other "smart" musicians over the past 40 years. Let's exclude all of the nostaglia acts [i.e. Rolling Stones, Kiss] who periodically tour their greatest hits only. Let's focus on the musicians who really use their brains in order to remain viable AND release new material...