I also own an 05 HHR, and they are similar. Opt for the ABS and side airbags. OnStar is super, worth the money. This car doesn't do anything super, but it doesn't do anything really bad either, and I paid $15,200 for my 08 with the automatic transmission and one year of on-star. Pinebelt "etched" my windows for $299 and said it was "standard procedure" although I didn't really want it. It was a pure money maker for them, but the deal was still sweet. If you want a reliable, good looking economy car, this is an excellent choice, and I would buy another one when in the market.
The info center monitors air pressure in the tires too!