My big trip to Turkey last 6 months: I spent a full semester studying in Istanbul, and exploring the rest of the country during my spare time. I never did a trip longer than 1 week in Turkey, but if you combine some of the destinations I visited, you can for sure build a nice long holiday trip to Turkey.
My selection for a big trip to Turkey
This list is not exhaustive as I do not pretend to write a complete guide with my travel blog. I have not visited all parts of Turkey and I am still adding posts to the blog about this region.