To add to what others here have already said, there is some evidence that, in the period between the attack on Pearl Harbor and the Battle of Midway, certain members of the Japanese political and military establishment (including, it seems, Yamamoto) advocated the occupation and perhaps annexation of the Hawaiian Islands. John J. Stephen discusses this at length in Hawaii Under the Rising Sun: Japan's Plans for Conquest After Pearl Harbor (Honolulu: University of Hawai'i Press, 1984), though it is somewhat outdated. I unfortunately don't have access to my copy at the moment, but if memory serves me correctly, military planners expected the support of the local Japanese-American population; this was wishful thinking, as Stephan demonstrates.

Another curiosity I've stumbled upon is the "Land Disposal Plan in the Greater East Asia Co-Prosperity Sphere," drafted by the Research Section of the Army Ministry in December 1941 (the text of it appears in the appendices of Richard Storry's The Double Patriots: A Study of Japanese Nationalism [Boston: Houghton Mifflin, 1957]; Stephan also refers to it in passing). The document outlines the administrative divisions for Japan's future (possibly decades later) conquests, and the section "Eastern Pacific Government-General" lists Hawaii alongside other Polynesian islands.

More intriguing is section 8, "Alaska Government-General," which includes "Alaska / The Yukon Province, and the land between that Province and the Mackenzie River / Alberta / British Columbia / The State of Washington." Under section 9, "The Government-General of Central America," we find "Guatemala / San Salvador / Honduras / British Honduras / Nicaragua / Costa Rica / Panama / Colombia, and the Maracaibo district of Venezuela / Ecuador / Cuba / Haiti / Dominica / Jamaica / Bahamas" with the comment that "the future of Trinidad, British and Dutch Guiana and British and French possessions in the Leeward Islands [is] to be decided by agreement between Japan and Germany after the war." Finally Section 10: "In the event of her declaring war on Japan, Mexico to cede territory east of Long. 95° 30’. Should Peru join in the war against Japan, it must cede territory north of Lat. 10°; and if Chile enters the war it shall cede the nitre zone north of Lat. 24°."

Beyond this, I highly doubt whether Japanese planners ever formulated concrete plans for the occupation of territories in the Americas. I would instead associate it with the "victory disease" that had spread among many Japanese in the aftermath of Pearl Harbor and their successful conquests throughout the Pacific.

Please forgive me for any errors or lapses in memory! :)

The direct reason for the Japanese attack against the US is because the Philippines, a US protectorate, lay directly in between the Japanese Home Islands and the Dutch East Indies. In addition to being a large metal producer, it also was home to the US Asiatic Fleet. Due to an embargo by the Allied powers (caused by the Japanese seizure of French Indochina), Japan was in desperate need of raw materials-especially scrap metal, and to a lesser extent oil-and to acquire those resources many felt that Japan needed to conquer Indonesia. However, there was a problem: the British would certainly protect the Dutch from a Japanese attack, and the US was already very displeased with Japanese actions in China. Thus, attacking the Dutch would also require neutralizing both the British forces on Malaya and the American forces at the Philippines. And the rationale further posited that an attack on the Philippines would also result in US intervention from the mainland, so Yamamoto believed that a strike on the US Pacific Fleet was necessary as well.

Japan's war plan was simple: there was no way that Japan could defeat the British, Dutch, and Americans in a long war. However, given the fact that the British and Dutch were distracted by the war with Germany, Japan believed that by building up a defensive perimeter, using island airbases to make up for Japan's inferior industrial and shipbuilding strength, they would be able to destroy the inevitable Allied counterattack, and reach a negotiated settlement to solve Japan's resource problem. It takes time to build airfields and fortifications, so Japan struck Pearl Harbor in an attempt to delay an American response long enough for Japan to build up its defenses for the American onslaught, whereby the so-called "Fleet Decisive Battle," or Kantai Kessen, would be fought.

So why, exactly, did the Japanese need the resources in the first place? The answer is China. Since 1937, Japan had been engaged with China in a brutal bloody struggle. While Japan had managed to capture many of the major population centers, including the Nationalist capital of Nanking by December 1937, Japan's progress since the initial flurry of success in coastal areas was minimal. The Nationalist Chinese had moved significant populations and industry to the interior, and had slowed the Japanese advance due to a combination of guerrilla tactics, controversial decisions like intentionally flooding a massive part of China, and the fact that Japanese logistics-already notoriously poor at the best of times-simply were unable to properly supply Japanese formations the deeper they went into China. Japan had been hoping for a quick victory-which is why their target priorities had been primarily on the Nationalist capitals of Nanjing, Wuhan and then Chongqing-but by 1941 they had made little progress.

However, Japan's internal politics made this unwinnable war a must-win war. During the interwar period, young military officers engaged in an uncoordinated but highly effective campaign of terror against the civilian government. Various influential industrialists and politicians-including the Prime Minister of Japan-were assassinated, and a coup attempt known as the 2-26 incident deeply frightened the Japanese government. While it was put down by other elements of the military, the ensuing chaos gave the military control of the civilian government, allowing them to shape policy. In effect, while the military was able to control the government's foreign policy, the government had virtually no control of the military.

This led to a deep, political problem. Any attempt at a peace without victory in China-which is what giving into the US demands to lift the sanctions would have amounted to-would almost certainly result in another coup by the military, which was more thoroughly in charge. At the same time, Japan did not have the resources to sustain more years of conflict in China, and the sanctions impeded her from getting more. There was a Catch-22 here, and Japan's choices were simple: risk civil war, or risk world war. They opted for the latter.

In other words, Japan needed to win the war in China, but they could not do so without either not winning the war in China, or by invading the Dutch colonies, which equaled war with the US and Britain as well. It was a choice of desperation, but then again, what war isn't?

Sources:

Saburo Ienaga, The Pacific War

Harmsen, Shanghai 1937: Stalingrad on the Yangtze

Evans, Kaigun

Parshing and Tully, Shattered Sword, et. al

Your question has been partly answered in response to http://www.reddit.com/r/AskHistorians/comments/20uxwd/why_did_japan_attack_pearl_harbor_rather_than/

Eri Hotta has done some remarkable work on the Pan-Asian ideology. I seriously recommend you check it out.

Must historians have the regular reasons such as mentioned in this thread: markets in China, international recognition of Manchukuo, recognition of the Wang Jigwei puppet regime, etc. But Hotta asserts that Japan's long term goals were not restricted to that. The Meishuron Pan-Asian ideology, guiding the concept of the Greater East Asia Co Prosperity Sphere, predates Japans expansionism in the 30's, and ultimately envisioned an Asia free of colonialism and 'guided' by Japan. Of course,Hotta concludes that Japan was already a colonial power and the course of the war began Japan's transformation into am Imperial power, halted only by its military losses and surrender.

Followup question - How did we transition from warring enemies to our good relations today?

be very careful with what you take as fact on this subreddit, there's a lot of censorship and "cherry picked" history