"The Right Place at the Right Time"

In the middle of our action-packed parasha sits an innocuous pasuk. "Avraham traveled from there to the Land of the Negev, and he lived between Kadesh and Shoor and dwelled in Grar" (Bereishit 20:1). Whenever someone as great as Avraham makes a decision to move, even if still within the Land, and the Torah decides to write about it, commentators (and hopefully we too) will want to know why he did so.
As usual, there is no better place to start than with Rashi. He posits that it has to do with the previous story, which dealt with the destruction of Sodom. He provides two specific reasons why that episode could have prompted Avraham to move: 1) after the destruction, there were fewer passersby with whom to interact; 2) word got out that his nephew, Lot, had cohabitated with his daughters, in the aftermath of the destruction, causing disgrace to Avraham. Rashi's general approach, that Avraham was, on some level, escaping, is supported by the words "traveled from there."
There are others who stress the positive gain of Avraham's moving. The Radak suggests that Avraham wanted to live in another region of the country in order to strengthen his hold on the gift of the Land, for the benefit of future generations of the nation that would emerge from him. The Seforno also takes a positive approach, in regard to what he could gain from his new location. He claims that Kadesh and Shoor were both large cities, so that being between them awarded him the opportunity to spread the "Name of Hashem" in prominent and apparently new areas where he had not previously done so sufficiently. It is of course a strategic question if one has more influence on the world by concentrating on the quantity of people or the quality of the impact.
Rav S.R. Hirsch has a fascinating explanation that teaches a lot about the importance one should give to education and the steps needed to ensure success in that realm. He says that since Avraham was told that his son from Sarah was soon to be born, he had to already prepare the proper environment for his upbringing. Avraham chose the southern, desert region, where it would be easier to achieve the environment of social isolation for his son, so that he not be harmed by spiritually dangerous influences. On the other hand, he said, Yitzchak would need some exposure to populations that thought differently than the way his father was teaching him. One who is totally isolated does not develop educational "antibodies" to outside "infection" and, upon finally being exposed, is likely to get very sick. Therefore, he chose a place in the desert place that was near populations, and, says Rav Hirsch, the Plishtim were a somewhat less corrupt nation than many of the Canaanites of the Land.
Indeed, when one moves, he is sometimes running away and sometimes running to. But, as we can learn from Rav Hirsch's commentary, the perfect environment is one that may need to be prepared years in advance and must provide a variety of almost self-contradictory resources and influences.