For some reason I thought this was a repost earlier, so I didn't respond to it. Sorry about that.
The MDX sounds like more vehicle than you need, and won't be nearly as much fun to drive as something smaller.
The G37 seems like a much better fit. I see no need for the X's all-wheel-drive in your part of the country unless you're in the mountains on the western edge of the state.
Among Acuras you might look for a TL SH-AWD. It's AWD system makes the car more fun to drive, but it's still not as sporty as the Infiniti.
Lexus offers the IS sedan. The 2014 IS might be available in your price range, though they do cost quite a bit more than a G37 of the same age. The 2006-2013 IS isn't as sporty as the newer one or the Infinity. The IS has been offered with two engines. You need the 350 for performance comparable to that of the other cars. The 250 feels much weaker, but if you don't have any need for quick acceleration it might be sufficient for your needs.