Best bet then would be the Cobalt, or if you can spring for a little extra, the Saturn Astra is superb. They sell like hotcakes in Europe. Very fuel efficient and well put together. Since it is new in the U.S. I can't say with certainty what reliability and resale value will be, but it is the nicest compact GM makes, and I think it will suit your needs well. Also, being a hatchback it is very practical as well. Insurance costs should be minimal, especially since pretty much every safety feature you want is standard. The base XE 5 door model starts at about the same price as a nicely equipped Cobalt, and has most of the features you'll really want as standard. I'd give it a look.
Avoid the Ion at all costs. It is one of the worst cars GM has made, and it is being discontinued after 2007 due to its replacement by the Astra. Resale value is non-existent. Nearly all cars have an MP3 jack on the radio now, so that's not really a feature worth mentioning.
If you don't mind going with a Honda, the Fit would be an excellent choice. It has very good fuel economy and by reputation I would imagine good resale value and reliability. Just beware that it is smaller than a Corolla, but it is packaged very efficiently so interior space is still pretty good. It can also be pretty hard to come by. It is being redesigned next year and should be even better, so if you can hold off until then and you can manage to find one, it could be a good choice too.
Hope that helps!
