I was listening to the Fountains of Wayne album Traffic and Weather on my ride back to Tallahassee when I realized that every song was about motion and romance. I started thinking that perhaps every FOW song was about these things. I hadn't thought really hard about it, but I ended up talking to TBW about it, and he reminded me that personal shortcomings are a big theme in FOW songs. I guess I should have thought of that one.
I think something else that they write (not necessarily about) is catchy pop songs. Vocal harmonies and catchy riffs along with sustained rhyme schemes kinda get their songs stuck in your head. I'm surprised that these factors along with the length of their average song that they don't have more radio success.