The criteria of the VWP states "The purpose of their stay in the United States is 90 days or less for tourism or business"+ and +"The traveller can demonstrate the intent to stay 90 days or less in the United States and demonstrate sufficient funds to support themselves while in the United States".
Because the word "intent" is part of the rule, even THINKING about trying to sneak across the border and re-enter is a violation of the program.
No, crossing into Canada will not let you re-enter and restart a 90 day period. You must leave North America under the terms of the program, not just the US.
No, attempting to enter at a different point will not allow you to sneak back in either. Everything is computerized, and every agent at every entry point will know of your previous entries, where and how they occurred.
Yes, there is a waiting period before you can re-enter on a new VWP 90-day period. The waiting period is an unspecified period of time. The border agent must be convinced your second entry is a new trip. A weekend trip to Buenos Aires is not going to convince them that you have satisfied the rules of the VWP. Remember that millions of people visit the country every year; border agents have seen every trick you could possibly think of.
And remember that being denied entry under VWP means you will never be eligible to use it again. You will always be required to apply for a visa (and may be denied that too). A denial of entry under VWP will have consequences in other countries too, as participating countries share information. If you want to stay in the US for more than 90 days, I strongly urge you to apply for a visa.
"Funny looking" stamps are not an issue for entry into the US, especially Israel. Thousands of Americans travel to Israel every year and the US government has extremely friendly relations with Israel.
For budget flights from the east coast to Cancun, look at Jetblue and USA 3000. The major carriers also serve this route, and may not be more expensive--American, United, Continental, USAirways. It is a competitive route.
DF handles all of the major carriers. Use a flight search website like kayak or expedia to compare costs.