from my limited experience of atlanta and houston, both seem worse traffic-wise than LA (which i know well). their traffic seems to be bad nearly everywhere, whereas traffic in LA has lots of hotspots, mostly in wealthy areas (coast and hills), where the demand for (sparse) housing has equilibriated poorly with insatiable demand for roads and parking. in the denser parts of LA, public transit and more walkable neighborhoods have kept traffic somewhat in check (bad maybe at rush hour, but not all the time).
