AIPAC does not represent all of Israel, but only the pro-war-with-Iran, anti-Palestinian-state arm of the Israeli government and their supporters. It intrudes into American politics not as a true friend, but as the mafia of foreign lobbying groups, using threats to strong-arm U.S. politicians into enacting policies contrary to the best interests of the American people.
Hillary Clinton will, of course, attend the conference to kiss Netanyahu's ring. He is in the U.S. trying to drum up support for a war against Iran, based upon the same bad logic America was coerced into supporting for the Iraq War (revealed in a speech by Philip Zelikow). Hillary is all for this, I'm sure, even though removing the Iranian government would leave only Hezbollah in power over a failed state, and would actually end in greater danger to Israel, which then would use its arsenal of nuclear weapons to start WWIII. (Of course, the fact that it won't sign the non-proliferation treaty is the ultimate pot-calling-kettle-black hypocrisy.)
And does Hillary Clinton also side with Dov Weisglass, the Sharon adviser, who stated during a Ha'aretz interview with Ari Shavit that Israel's goal was to put the peace process "in formaldehyde" "until the Palestinians turn into Finns" (thus proving that they have been playing America for fools)? Presumably, this is to buy time to build more illegal West Bank settlements for extremists who beat up Palestinian children while IDF forces look the other way.
America pays and pays and pays for supporting these terrible policies, and also foots much of the bill for Israel's (expensive) military occupation. We pay in blood as well, in terms of anti-U.S. sentiment and terrorism throughout the world. Likud/AIPAC is like the "friend" who constantly mooches off of you, then is nowhere to be found when you need help.