If I could do only one trip to the Middle East to learn about the Bible, I would go to Israel. Second, Turkey and Greece, though for most only western Turkey would be included in the itinerary (and I profited more from eastern Turkey than western). Jordan and Egypt would be next. Near the bottom of the list would be the islands of Cyprus, Crete, Malta, Rhodes, and the city of Rome. If someone can do it all, then they’ll gain from it, but most have to choose one or two trips, and for that, I recommend they skip some things. But this recommendation probably isn’t necessary because there aren’t many trips going to these places as part of a biblical tour anyway. I can’t speak to Lebanon, Syria, Iraq and Iran because I haven’t been. Yet. I do think a second trip to Israel is worthwhile, moreso than a first trip to some of the biblical countries.
I would not recommend someone to try to do Israel and Turkey/Greece on the same trip. This is because there is just so much to digest and you don’t have the time necessary to do that if the two are put together on an initial trip. Israel largely introduces one to the Old Testament world; Turkey and Greece are a new window into the NT arena. I do believe understanding these “worlds” is very valuable for understanding the Scriptures, even apart from seeing the biblical sites themselves. You just understand Paul better when you see the gods they were worshipping in his day, see the temples that dominated the cities, and see the way of life of the Greek people.