Tunisia is particularly interesting because it is the most Westernized of the Arab nations undergoing upheaval, with a large, educated middle class and a strong women's movement. Tunisia was also the first country to dump its ruler, by spontaneous, peaceful demonstrations in January. These attributes should give it better odds of transitioning to democracy.
Yet its best-organized political party is the Islamist Al-Nahda, which will probably get 25 percent to 35 percent of the vote in Sunday's elections. Although Al-Nahda's leaders publicly proclaim their acceptance of pluralism and tolerance, many secular Tunisians believe they have a hidden agenda.
And in the run-up to elections, Tunis is transfixed by the brutality of hard-line salafi Islamists (much more extreme than Al-Nahda), who attacked a TV station that showed the award-winning film Persepolis. The film is a memoir of a rebellious girl growing up during the Iranian revolution, but the salafists say it insults Islam.
If Al-Nahda does well, its success will be due as much to organizational skills as to ideology. It has been able to appeal to the poor and unemployed in Tunisia's rural regions. An Islamist plurality at the polls will test the ability of non-Islamist parties to cooperate, especially on writing a new constitution.
Already, the Tunisian debate about the compatibility of Islam and democracy is the most sophisticated in the Arab world, which is why it's so important to pay attention. Tiny Tunisia could demonstrate whether "moderate Islamists" could operate within a secular constitutional framework - or not.
Far more problematic - and far more important - is Egypt, traditionally the leader of the Arab world. Nine months after the Tahrir revolt, the country is enmeshed in a three-way struggle among weak secular parties, well-organized Islamists, and a military that is maneuvering to keep its perks and powerful role.
A stable Egypt is vital for the region at a time when Syria and Yemen are still convulsed with violence and when Libya's future is murky. But developments in Cairo illustrate the unpredictable course of the Arab awakening. They also demonstrate the diminished level of U.S. leverage in the new Middle East.
Egypt's military wants to maintain its peace treaty with Israel; it receives substantial U.S. aid, which should give U.S. officials leverage. Yet Egypt's generals must now listen to their newly awakened citizens. They may crack down or distract the crowds by encouraging sectarian violence. They will manipulate state media and blame Egypt's problems on outside agitators.
But they can't entirely ignore public opinion that has become increasingly anti-American and anti-Israel. And they must tolerate, or even cultivate, the Islamists, whose parties will probably win the largest bloc of seats in coming elections.
Any U.S. administration - Democratic or Republican - will have to deal with an Egypt that is far less predictable and less friendly than the previous regime.
There are no formulas that can be applied to the fluid situation in Tunisia and Egypt, let alone to a Syria, where regime overthrow is even more likely to usher in strong Islamist forces. On this trip, I'll be trying to divine which U.S. policies might be most helpful to the forces of Arab moderation, or at least do them no harm.
Into this mix, one must also factor the end of the Israeli-Palestinian peace process. Israel's exchange of 1,000 Palestinian prisoners with Hamas for the captured Israeli soldier Gilad Shalit will likely strengthen that extremist group and make the resumption of peace talks even less likely.
I've argued that the U.S. administration - and Israel's government, too - should have embraced Palestinian Authority President Mahmoud Abbas' efforts to seek recognition from the United Nations. That approach would have reinvigorated the two-state idea pending future negotiations. Didn't happen.
The end of the peace process will affect the whole region in ways that few have begun to consider.
I will be asking Israelis and Palestinians for their predictions.
The Arab revolutions are far from over. We are in the eye of the storm.
E-mail columnist Trudy Rubin