I too have a 240 (1991) that I fell in love with and RR's everthing imaginable..it now runs great. In the process, I fell in love with the 940 and about 2 months ago, bought a 940. Thanks to this board, I knew to stay away from the Diesel and the 960. The 940 has the same engine, tranny and drive train as the 240, with minor improvements. So far, the main differences I have found are:

Smoother, quieter ride
Better handling
more sporty body style
No history of water leaks around 940 windshields to rot the floorboards
No history of nightmarish rear taillight PCB problems

Although I could be wrong, I have to disagree with other post stating 940s have nivomat shock system. Mine does not. To the best of my knowledge, the nivomat shock system is basically a form of Indep Rearwheel Suspension, and EXTREMELY expensive; one reason to avoid the 960. If you search the archives, you should find plenty to read about the nivomat system and precisely which vehicles had it installed.