Although not as unique and photo friendly, the grand structures in the eastern sections are definitely worth your time. They belong to Byzantine times, but lends much of the style on Roman patterns. The main causeway out here is of such an outstading quality that you may actually just use it for its purpose without realizing that it is between 1500 and 2000 years old.
The Byzantine basilica is very nice with its extensive floors of abstract mosaics.
If your Xanthos experience is paired with a visit to the British Museum, London, UK, head on a bit south to see the original location of the Nereid Monument.