I just purchased my 968 CV last month and all I really drove it was from Seattle up to the Canadian border and then home to Langley last week.
I also went shopping for a Miata with my 16 year old daughter two days ago and I need to tell you that these are COMPLETELY different cars! The 968 handles like a serious road machine and you are well advised to have both hands on the steering, since it just hugs the road and will follow contours, dips, ruts, etc if you are not attentive (that is why PORSCHE did not provide cup holders in the 968). YET... it just begs to be pushed. It was OK at 60 on the interstate, but when I punched it to 80, that is when you could just feel the car just throb in contentment!
On the other hand, the Miata is a "toy" compared to the 968. Fun to drive, but it feels very lightweight and it has a soft/pleasant suspension. The Miata will be a great car for my inexperienced daughter, but if you want to have FUN while driving, get the 968. The feeling in a Miata is "Weeeeeee, here I come!", while in the 968 it will be more like "UH - YAAA (with some serious guttural tones)!
Look forward to hearing about your possible upcoming test rides. May you be "bitten by the 968 bug"!