Very Good Thread.
I have looked at couple of exotics but I am not the type that will get into something that is going to get crap loads of attention and scream "Look at me People"
As you stated M3 is a great all around car and may be a good alternative (when kids are gone) might be a 911.
To me a good balanced garage these days can be E90 M3, 911TT (or even C4S / T4S) and a Cayenne GTS...... anything more than that you are showing off waaay too much for my taste.
Current: 2016 F10 535i xDrive AW w/ Black Dakota, ZMM, ZCW, ZDA, ZDB, ZPP, 688 & Black Grills.
Retired: 2011 E92 M3 -AW
....ED April 29th, 2010
Retired: 2007 E92 335i -Space Gray.....ED Oct 19th, 2006