I would qualify the "get the extended warranty" with "since it's an American car."
I'm not knocking the Pontiac, and I really like the look of the G5, but it is pretty much a fact with cars that American cars break down more. It's actually another reason to feel good about the lease option you're taking - you will be driving that car for the first 4 years on the road, and from the sounds of it, it wont actually get much mileage, so you should be fine. If it turns out to be a problem car, you don't own it, the warranty should cover most of the problems, and you can get a new one at the end of the lease term!
I've only ever had 3 cars - 2 Toyotas and a Cavalier Z24. The Cavalier was by far the most fun to drive, but most of the time, I was driving it to the shop.. but, I bought it used and didn't really know what I was doing when I bought it, I guess.
Anyway, enjoy the freedom - I know how exciting that first car can be. I still have mine - a '98 Corolla, and everytime my wife suggests we should trade it in for something bigger, a tear comes to my eye (well, maybe that's an exaggeration, but you know what I mean.
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Andrew