My personal opinion is I'd go with the SS turbo'd cobalt. I love the look of those, plus the wheels they come with ;) but at the same time like you said the sedan is hard to find. but me personally, being a snowboarder. all I need is something that i can throw a roofrack in and a few friends, with bags in the back so both work. depending on what you want to carry, you can always get a thule basket for the roof. given if your closer to starting a family, or do road trips with friends, or anything along those lines I'd get the HHR ss and be more unique with mods on that. (personally havent seen 1 modded HHR here where I live.) but the main reason I'd go with the SS turbo'd balt is because Here, we are surrounded by mustang owners and neon owners that beak us, and given that I drive a 2006 LT I can't really do much to shut them out, (except the fact that I have Halos and LED taillights, I look fancier then them in the dark.) We have 2 guys in the community that shut half of them up on the track with their balts. (both turbo'd.)
Thats my opinion. I'd go SS turbo Balt.