Yes we did the same with knossos, we drove there and wandered around on our own, as we had friends with and also as we came from Chania it was a huge journey. I have always regreted it

as although we bought a guide book we timed it wrong for an organised tour and it would have meant hanging about in 38 degrees waiting for one to start, so we just plodded ahead. I don't suppose I will ever get back there

and wish I had gone on the arranged tour as I am sure I would have got far more from the experience and have left with a better understanding of what we had seen.
Whereas in Turkey we went on an organised tour to certain historical sights and it was the best money we spent all holiday, the guide was superb.

and it was a very rewarding experience.