There are 8.9 million millionaire households in the U.S., up nearly 50% in two years. The heads of those households could fill 100 football stadiums the size of Notre Dame's. But even if millionaires are now a common species, they are hardly homogenous. Just ask cultural anthropologist Larry Samuel of the firm Culture Planning.

Although he works mainly for financial advisory services, he may be on to something where prospect research, cultivation and fundraising solicitation are concerned. Samuel studies the ways of the rich for JP Morgan Asset Management, mostly through field observations in New York, Miami Beach and other money spots. Samuel says doormen at posh buildings are fonts of anthropological wisdom.

Samuel has thus classified American millionaires into five archetypes, each with its own “Passion Points”, consuming habits, and style, as follows:

Thrillionaires. These are Thorstein Veblen's conspicuous consumers: generally insecure people who thirst for privacy and exclusivity, and for whom objects and a first-class lifestyle are a constant reminder of status and success. Well-known exemplar: Donald Trump. Natural habitat: Las Vegas; Boca Raton, Fla.

Coolionaires. These rich aesthetes may not work in creative fields, but they view creativity as the essence of life. They plow cash into fine art, cool architecture, and benefits at the New York Public Library. Money is, in Samuel's words, an “opportunity to express one's status as a person of refinement and sophistication.” Well-known exemplars: disgraced opera impresario Alberto Vilar, money manager/utopian community developer Boykin Curry. Natural habitat: Manhattan below 14th Street.

Realionaires: Practical, unassuming types. These people like to live under the radar and stay out of gossip columns. While they hate to spend money unnecessarily, “they're willing to splurge on things that matter to them,” notes Samuel. “Ivy League Schools, Stickley furniture, professional appliances.” They have an affinity for big-ticket, brand-name items because they deliver value, not status. Well-known exemplar: Warren Buffett. Natural habitat: The Midwest.

Wellionaires: Spiritual rich folks who view life in holistic terms. They're willing to splurge to make sure they look good, feel healthy, and stay in good shape. They're open to therapy, New Age thinking, and alternative medicine. Well-known exemplars: disgraced former Time Warner CEO Gerald Levin, Los Angeles Lakers coach Phil Jackson, Oprah. Natural habitat: Sedona, Ariz.; Santa Monica, Calif.

Willionaires: What used to be known as Old Money. These are people who recognize their privilege and responsibility to leave the world a better place than they found it. Social entrepreneurs, they're interested in their legacy and maintaining traditions. They view philanthropy as a way of life. Well-known exemplars: David Rockefeller, Bill Gates. Natural Habitat: Maine, Park Avenue.

Daniel Gross, who writes the Moneybox column for Slate says, “Such archetyping is a fun enterprise. Most anthropologists conduct research while living in a hut in rural Indonesia. Samuel and a group of stringers fan out into markets thick with millionaires and take notes. When I spoke to Samuel this morning, he was in the field—in Miami: 'There's a DJ and hip-hop conference going on here, and there's lots of bling, I've seen several Rolls Royces.' (Clearly, rappers are thrillionaires, not willionaires.)”