Keli, I could have written your post 4 years ago. We had a Saturn with over 150,000 miles and it was just done. We seriously looked at the Civic, Corolla, Mazda 3, and Impreza. Also, we just went to the Auto Show last night, so I have some thoughts on these cars
After the auto show last night, I was in love with the Impreza. It is so cute!! The gas mileage is worse than the other cars above, but it is AWD, so if you live in a place with yucky winter weather I would totally get this car.
Civic - DH and I decided to buy this car in 2004. It's very practical and cute and is a fine car. Like others have said, both Civics and Corollas will hold their value well. I am not sure if you drive on highways much, but I find the road noise inside the Civic to be pretty loud (at least compared to our Passat). I'm not sure if it's just my car or if that has changed over the last 4 years.
Mazda 3 - DH and I test drove one of these and I didn't like it at all. It had some weird blind spots going on and I thought it cost more than it was worth. Not too thrilled with it, but could definitely be someone else's cup o' tea.
Elantra - I had never thought much about Hyudai before, but I saw it last night and it is really cute. I haven't driven one though.
Let us know what you decide!