I just wanted to update this and thank everyone for their great advice. It's really come in handy. We were able to stretch out the use of her Cavalier a bit longer, but now it has come to the point where it has started leaking fluids in our garage. So we'll probably close a deal on a car this weekend.
We followed the great advice everyone posted here and it seems like we've got a couple of good deals on the table. We researched cars using edmunds.com, kbb.com, and consumerreports.org, then test drove a few different vehicles to see which one my wife liked the best. Then we requested quotes online. It seems like most of the GM dealers around here just automatically give you invoice as your starting price as an internet customer. We also talked to one of my wife's friends at work, who said her husband can hook us up with GM's "In the Driveway" program. We haven't yet heard back on that though, because her husband forgot his PIN. So then we went back to the dealer we talked to before. The salesperson said that "In the Driveway" is invoice pricing, so it looks like it's about the same either way. In any case, they're willing to match. On top of that, we can get the rebates and other incentives to lower the price a bit. The best part is that we haven't said anything about the points my wife has on her GM card, which should drop the price further another $1000-2000.
It looks like my wife is going for a Pontiac G6 GT. Does anyone have one of these out there? I kind of interested to hear what you think of the automatic /"tap shift" manual transmission. After the discussions of manual v. automatic, I thought maybe the answer might be both.