If you are open to Wagon's, you might consider a VW Sportwagon. Very fun to drive and affordable - while having cargo space similar to a Rav-4 size SUV. Nice interior. Should be able to find something lightly used for $18k. Newer VW's are much more reliable than 10-15 years ago. Far more space than the Volvo V-60 and other compact wagon's. We have a family of 5 and the kids fit in it fine.
Of course you can't go wrong with a pre owned Honda, Subaru or Toyota as they will be plenty reliable, you just give up a little in mileage and the "fun to drive" catagory over the VW. Also, they hold their value, so you might get an older car for the money. You might also consider the Mazda CX-5.
Edit: looks like I accidently tagged the Sportsvan instead of Sportwagen in my recommendations. Sorry!