kja and neckervd, thanks for your help. Is it advisable to do a tour group with either of these hikes? kja, what are your thoughts on the Imbros Gorge?
Also, thanks for airport tips.

I visited the Imbros Gorge by myself, but after I rented a car so I could reach it's starting point. I enjoyed that walk immensely! Post #48; scroll down...
With Gratitude for a Glorious Solo Month in Greece

Nobody needs a guide for the Samaria Gorge hike.
But be aware that there is no road from the end of the gorge (Agia Roumeli) to the starting point (Omalos).
From Agia Roumeli one goes usually by boat to Chora Sfakio and then by bus to the North up to Vryses on the Chania- Rethymno highway.
It's easy to buy bus ticket from Chania to Omalos and from Agia Roumeli to Chania as swell as boat tickets may be a day ahead and to do the whole thing without any guided tour..