Visited, December, 2010. All components but as other locations (Al-Balid, Wadi Dawkah and Sumhuram) are easily accessible I will focus on the lost city of Ubar.

Shisr or Ubar (Wubar) can be visited by normal car right now. If driving from Salalah just go around 40 km north of Thumrayt where you can take well sealed road to Shasar (oficial name of Shisr at least on roads signposts) total lenght is around 50 km where at least half of it is asphalted, the rest is normal dirty Omani road but accessible on normal car. I doubt if there is any form of public transport to get to the village.

The site is really for the most desperate persons, not very spectacular but at least interesting enough to make a journey. It is well marked with plates and descriptions of seperate archeological findings (Arabic and English), fenced and yet free of charge. As there are speculations if the place is really Ubar you can decide on your own. For me the most spectacular place there was a huge cave partly colapsed - main reason for abandoning the place. Photo attached shows the remains of the fortress or an administrative structure (upper part of the city).