Having just returned from a two week Sierra Club trip to Greece, I feel obligated to share my experience. I'll attempt to be brief. To paraphrase Mark Twain in his autobiography, there's no possible way to go into detail. And the experience is in the details.
For me, seeing and being in Greece was a once in a lifetime highlight. I mean the history, geography, culture. I was transported back in time over and over again. I've seen photos of the Parthenon dozens of times, but to be standing right there makes your jaw drop.
We landed in Athens and quickly ferried off to Tinos Island, where we hiked the "back country" for three days (with a local guide--and most every citizen speaks some English). We repeated the itinerary on both Naxos and Amorgos. Each island was somewhat different, yet similar. Hikes usually involved a particular destination--monastary, village, mountain top, etc., ranging from 5 to 9 miles over rugged, rocky trails (I twisted my ankle once). While warned (prior to signing up) that the hiking would be strenuous, several members of the party were grossly overweight or out of shape. One lady hiked only one day out of 9. (some people are so stupid) We returned to Athens for a day of site-seeing. Some of us witnessed the "lighting of the Olympic torch" ceremonies (going to the Winter games in Russia). Museums, relics, ancient Agora, the Acropolis, street vendors, cafes, etc. etc., all added to the glory of Greece.
Personally, I overate (My goodness, the food was fantastic!!) and I felt great. The weather was beautiful (but they need rain), the scenery spectacular. I took 200 photos which barely covered the things I saw. The group was compatible, although there are always one or two individuals that are irritating.
We overdosed on churches. I saw my share of crosses, icons, and Jesus paintings. But I did attend a great jazz concert in a "castle" with a gorgeous 21 year old girl sitting next to me (French Canadian)! That may have been the highlight of my trip!
I've since recovered from long and delayed air flights. You can't have everything perfect. Otherwise, the trip was "too marvelous for words".