looking at buying a 2006 S60 R model with 68000 miles. What should I look for? Any reliability problems or any big ticket repairs required? what fails on these cars? What kind of mileage can I expect? Thanks

If it is a manual you are in probably good shape. It is a nice car, the sport suspension may be a bit harsh for your wife, but it does corner very well.

No major flaws.
--
My name is Klaus and I am a V♂lv♂holic

Thanks Klaus, wondering if your comment about it being a manual meaning it's preferable - does that imply the Autos in 2006 S60's aren't desirable? Looking at one today...

What I meant to imply: Someone who does 'performance enhancements' and has an automatic, probably has done a few 0-60 runs that start off with 5000 rpm shifts to 1st! Or red lines the 1st and 2nd gear shifts. Neither of which are good for an autobox, regardless of manufacture.

--
My name is Klaus and I am a V♂lv♂holic

the standard faire would be worthwhile checking, oil changes (really should be full synthetic) on this car due to the high pressure boost, don't be turned off by odds and ends that need help (tie rods, sway bar links) - depending where you are and where the car has been they may be time for replacement.