Travel search site processed a whopping 443 million searches in the first half of 2011. There is an information gold mine buried in those hotel and flight queries, as well as answers to some of our most pressing travel questions: Is it too late to get an affordable plane ticket for the holidays? Are you paying more than average for airfare? What days of the week are cheapest to fly?

We asked Kayak and the company responded with tons of delicious data, which the folks at helped us assemble into an original infographic, below.

The most important bit is this: The best time to buy a plane ticket for the December holidays is the first week of December, up until the 10th. You still have time! And if you don’t have a ticket for Thanksgiving yet, well, family is more important than money.

Kayak has engineers from its analytics and marketing teams constantly crunching numbers and dissecting customer behavior to find useful nuggets of information. That data is used to inform design and tweak searches, but it can also turn up coveted booking tips for travelers. For example, don’t don’t buy plane tickets more than 30 day in advance or within 14 days of your trip.

These tips apply no matter what site you use to search for plane tickets. Kayak queries over a 100 sources for its results, including ITA, the travel software giant recently bought by Google. Google uses ITA to power its new competing flight search. Bing also has its own search function that, it turns out, is powered by Kayak.

Here is a look at other key Thanksgiving, December holiday and New Year’s Eve travel booking and price patterns:

Infographic designed by