My wife and I and our 4 kids (ages 9, 16, 20, and 22) did a private tour with Athens Tour Company in late May. We had an amazing time. Nikos, our driver, did a marvelous time making sure we were at the right place at the right time (e.g. we drove up to the changing of the guard at the Presidential Palace with about 90 seconds to spare) and we were able to see most of the major sights in Athens. Helen, our tour guide, was also great. She was a wealth of information at all the places we toured and arranged our day so we were minimally impacts by the large tour bus crowds. I highly recommend their services.