[ezmaass]

Comfort 95% of the time. If you're driving casually, Comfort is probably the best mode as it won't hold the revs too high, helping gas mileage, easing transmission shifts, and generally making for a smoother ride (between transmission shift points/speed and damper rates if so equipped).

I generally only change to Sport if I'm in a real rush to get somewhere and know I'll be flogging the car a bit. This becomes a bit of a must as the stiffer suspension is needed to control the weight of the car in harder corners. The more "ready" transmission (holding lower gears) is generally also nice for more aggressive driving, helping to reduce the amount of throttle input needed. Overall, the car is just more alert and agile. But again, I don't find myself putting the car in Sport all that often, since normal driving becomes a bit too twitchy and unnecessarily wasteful of gas.

As for Sport+, I think I tried it only once. I don't believe it does anything other than give you more leeway with the removal of some driver's aids... and the ability to use launch control. It's almost silly that it's included, along with launch control for that matter, in a 4400lb luxury sedan.