Going to Greece
This is a photo trip so I would not recommend cutting back on your gear.
Should you have to however, here are some thought from someone who lives in Greece.
1) 17-55 for sure. Versatile and best walk around
2) 12-24 A must have. At times you will be at tight places, narrow streets and it will be handy. I have prsonally found my 10-20 very useful in my trips.
3) 80-200. You will use it seldom. But always handy when looking for distant objects or things you can't get any closer.
Prepare with some good walking shoes. The weather is much nicer, cooler and fall is perhaps one of the best seasons. The harsh summer light is gone. Not many filters you will need.
Care to share the schedule of this trip? I may be able to give more tips. Again I live in Greece.